The Imps were more than worthy of the point on the road against their table-topping hosts and carved out the better of the chances in a game which saw both sides finish with 10 men.
A deflected Alan Power strike gave City a ninth minute lead but, after goalkeeper David Preece was forced off with a head injury following a late challenge by Joe Colbeck who escaped punishment, the home side levelled when defender Ian Miller hooked home after the Imps failed to clear a free-kick.
The remainder of the chances came at the other end with Jake Sheridan appearing to restore the lead shortly before the break only for the assistant to keep his flag down after the midfielder's header appeared to cross the line before being palmed away by a defender.
In the second half Sheridan was involved in an incident which led to Aswad Thomas seeing red after the pair scuffled after the Town man blocked the City man off the ball whilst the game ended with substitute Adam Smith handed his marching orders after referee Karl Evans deemed he'd gone over the top in a challenge on Bradley Wood.
There were four changes to the starting line-up for this New Year's Day derby clash against Grimsby Town at Blundell Park. With injuries ruling out Peter Gilbert and Gary Mills, Scott Garner and Dan Gray returned to the team whilst there were also recalls for Nicky Nicolau and Jamie Taylor with David Gilbert and Colin Larkin dropping to the bench. Grimsby named the same 16 as they did for their Boxing Day success at Sincil Bank.
Karl Evans was the referee and with a distinct chill in the air, he got things underway with City kicking off.
The Imps were the first to push forward with some early pressure ending with Alan Power forcing a corner but Nicolau's near post delivery was headed away by Craig Disley. Gray's subsequent throw-in was cleared before Marcus Marshall's counter-attack ended with his centre being claimed by David Preece.
Scott Garner was the recipient of a fifth minute caution for a high boot on Marshall, although the Grimsby winger appeared to duck into the challenge. Joe Colbeck's free-kick was headed behind by Power with City dealing with the resultant corner.
At the other end Nicolau was unlucky to see the ball run away from him following some decent build-up play down the right but it wasn't long before the Imps were pushing forward again and when a long Gray throw-in wasn't cleared, Power drilled in a low effort and, thanks to a deflection off a home defender, the ball wrong-footed James McKeown before nestling in the bottom corner of the net.
Grimsby's response came three minutes later with Preece doing well to palm a cross and when he blocked a Colbeck drive from the loose ball, the experienced stopper smothered before being grounded by Colbeck who clearly left a boot in on him. The referee's assistant spotted the infringement with players from both sides airing their views at the officials, including home 'keeper McKeown who sprinted the length of the field to get involved.
Once things calmed down, Preece was able to receive treatment from Kev Oxby before McKeown was booked by referee Evans. The official then spoke to Colbeck but he amazingly escaped punishment.
Preece was clearly in some discomfort and although he tried to carry on, he was forced off six minutes later with Paul Farman coming on as his replacement.
Farman's first taste of the action was, unfortunately, to pick the ball out of the net as, when a free-kick from Colbeck - fortunate to even be on the pitch - wasn't cleared with centre-back Ian Miller hooking an effort home via the inside of the left-hand upright.
City's response saw them win a corner, but this was delayed after an idiotic home supporter decided to stage a one-man pitch invasion. When it was taken, McKeown punched Nicolau's delivery away. Shortly afterwards, McKeown was forced to claim a low Jake Sheridan effort after he ghosted into the box to meet a Taylor centre.
The next attack from the Imps ended with Nicolau testing McKeown with a low effort and as the ball ran free the 'keeper came close to upending Oliver but the City striker stayed on his feet only for the ball to run away from a blue-shirted team mate.
Oliver then saw a powerful drive blocked by the busy Grimsby 'keeper before Boyce was denied when he had an effort hit McKeown on the arm before bouncing up off the bar. Taylor's follow-up header was palmed behind by McKeown.
The Imps remained on the offensive with Sheridan having a long-range effort deflect over but again the Town defence stood firm when the corner was played into the mix.
With the half in its last five minutes pressure from Oliver on McKeown saw the latter slice a clearance for a corner which was headed out for a seventh City flag-kick which was played short to Sheridan who was quickly closed down.
The pressure continued and when Nicolau picked out Sheridan with a deep centre, the City number 12 saw his downward header appear to cross the line before Pond seemed to palm the ball out with his hand but Sheridan's appeals to assistant referee Alix Pashley, who didn't appear to be up with play, fell on deaf ears.
A rare Grimsby attack ended with Nicolau upending Colbeck earning a caution for his troubles before the Fourth Official indicated that a minimum of five minutes were to be added on.
HT: Grimsby 1 Imps 1
Both teams emerged unchanged for the start of the second half and the Imps were the first to press with some quick attack play looking to see them unlock the Mariners defence for a second time; Oliver and Power both having shots charged down from the edge of the box in the first five minutes.
A sweeping City move 10 minutes after the restart saw Nicolau break down the left only for his ball into the box to be hacked behind by Pond with Garner heading the resultant corner over the bar.
Shortly afterwards Taylor curled goalwards only for McKeown to deny him with a flying save at full stretch to his left before the Town 'keeper claimed Sheridan's follow-up ball into the box.
The home side replaced Greg Pearson with Dayle Southwell shortly before the hour mark and this brought about some Town pressure with Marshall winning a corner on their left. This was played hard into the box by Colbeck and straight out for a throw-in on the opposite side.
City's response saw them force their ninth corner of the game but this was brought to an abrupt halt with referee Evans spotting a push in the box by an Imps' man. City's next attack saw Power chip an effort wide after Oliver beat Pond to a header whilst a minute later a long Gray throw was headed over by Boyce at full stretch.
At the other end a Boyce foul on Cook saw the hosts swing in a free-kick which was flicked on 12 yards out only for Farman to keep the ball out at full stretch before the City bodies were thrown on the line to keep the ball out. City duly counter-attacked but the final ball went begging.
With 20 minutes remaining Sheridan was blocked off the ball by Thomas and with both players on the floor the Grimsby man appeared to react and for the second time in the game there was a melee of players. Referee Evans was quickly on the scene and brandished a red card to the Town full-back before Tom Miller was cautioned for his part in the incident.
Left-back Bradley Wood immediately replaced the right sided Colbeck for the home side whilst the Imps' second change came five minutes later with Colin Larkin coming on for Nicky Nicolau.
In the 81st minute a Sheridan trip on Marshall earned the Citty man a booking and before the free-kick was taken Michael Rankine came on for Andy Cook for the home side.
Larkin's first taste of the action saw him cut in from the left before seeing his cross deflect out for a corner and when this was cleared back to taker Power, his second ball into the box ended up with Garner seeing his spectacular volley fly just wide.
A late challenge on Sheridan saw Wood become the latest recipient of a yellow card before Disley joined him for delaying the taking of a City free-kick. Adam Smith then replaced Jake Sheridan with the clock showing 88 minutes played.
Four added minutes was indicated and in the first 30 seconds of these Taylor set up Power who saw his low effort clip a Town man before going for a corner which came to nothing. Play immediately switched to the other end and after Marshall went on a surging run his effort was superbly blocked by Boyce before Smith was fouled by Rankine on the six-yard line.
Seconds after Smith returned to the fray he went in on Wood before sprinting forward with the ball, claiming he had won it, but the assistant was quick to flag and referee Evans even quicker to dish out his second red card of the afternoon.
This proved to be the last action of a pulsating local derby with City more than worthy of the point on the road against their table-topping hosts.
FT: Grimsby 1 Imps 1
City: David Preece, Tom Miller, Andrew Boyce, Scott Garner, Paul Robson, Dan Gray, Alan Power, Nicky Nicolau, Jake Sheridan, Jamie Taylor, Vadaine Oliver.
subs: Adam Smith (for Sheridan 88), Colin Larkin (for Nicolau 78), David Morgan, Conner Robinson, Paul Farman (for Preece 18).
goals: Power (9)
bookings: Garner (5), Nicolau (45), T Miller (72), Sheridan (81)
sending off: Smith (90+4)
Grimsby: James McKeown, Sam Hatton, Aswad Thomas, Ian Miller, Nathan Pond, Derek Niven, Craig Disley, Joe Colbeck, Marcus Marshall, Andy Cook, Greg Pearson.
subs: Shaun Pearson, Bradley Wood (for Colbeck 73), Dayle Southwell (for G Pearson 59), Andi Thanoj, Michael Rankine.
goals: I Miller (22)
bookings: McKeown (12), Wood (86), Disley (88)
sending off: Thomas (71)
Referee: Karl Evans
Assistants: Alix Pashley & Luke Watson
Fourth Official: Jamie Waters
Attendance: 7,405 (553 City supporters)