Exeter City were denied all three points at Vale Park as Idris Kanu headed home in the seventh-minute of stoppage time to deny the Grecians a hard-earned victory.
Matt Taylor’s men nudged themselves in front when Nicky Law side-footed home a well-worked goal in the 48th-minute and then they defended resolutely to keep Port Vale out heading into what, by the fourth-official, was deemed to be five minutes of injury-time.
However, with 96 minutes on the clock, the referee allowed Port Vale to take one more corner and from Tom Conlon's cross the ball dropped kindly for Kanu to nod home and give the host an unlikely point.
It was a cruel blow for City, who themselves could have wrapped the game up in the closing stages of the match when Lee Martin and Dean Moxey had close-range efforts blocked.
City went into the match having won their last four games in all competitions, while Port Vale were unbeaten in three.
It was, perhaps, then no surprise that both managers named an unchanged team from their last Sky Bet League Two fixtures.
City began the match brightly with Law playing a ball across the face of goal that Leon Legge had to hook out of the six-yard box before the hosts began to grow into the game. They had the first effort on target after 11 minutes when Ricky Miller shot tamely at Christy Pym. Miller then dragged a left-foot shot wide from just inside the box moments later.
Tom Pope also glanced a header off target after 25 minutes before City began to stamp their authority on the match once more. Hiram Boateng had a good shot from inside the box well blocked by Nathan Smith before Law fired over from 10 yards after a cross fell kindly to him.
Jake Taylor looked as though he was going to give City the lead after 35 minutes but his fiercely-struck shot, which was on course for the back of the net, deflected behind for a corner. Another chance then fell to Taylor three minutes before the break as Law fizzed a ball into him, but the Grecians midfielder sent an effort just over the upright.
However, a minute later, came the moment of the first half as Conlon unleashed a well-struck shot from 20 yards out that was heading to the top corner before Pym produced a top-class save to tip the effort onto his crossbar.
The second half was only three minutes old when City took the lead with a superb team goal. Pierce Sweeney and Taylor worked a quick free-kick well to send Lee Martin in down the left side of the box and he found Boateng in the area, who squared a ball for Law to tap home from six yards out.
Port Vale almost responded immediately but Aaron Martin got a brave header on a cross to deny Pope and then Miller followed up to fire a shot into the side netting.
Conlon then sent a free-kick wide before setting up Ben Whitfield for a chance that he blazed over. City continued to soak up the home side’s pressure well though with Dean Moxey clearing a Pope cross and Sweeney and Aaron Martin getting a number of telling headers in the area.
Then, after Conlon swung a free-kick into the box, Pym made a brave punch and got clattered by a poor challenge from Leon Legge. That created a bit of stoppage time to add on at the end of the match but, when the fourth official indicated that there would be five minutes of injury time, City went about trying to finish the game off.
First Lee Martin had a close-range effort blocked by Scott Brown and Dean Moxey followed up to race into the area and hit another effort that a home defender threw himself in front of. Those misses appeared not to matter though as the game went beyond the 95-minute mark, but the match went on into the 99th minute - four obver the minimum that was scheduled - and Port Vale managed to find the back of in that time.
Port Vale: Brown, Rawlinson, Smith, Legge, Clark, Whitfield, Conlon, Oyeleke, Hannant, Miller (Kanu, 70), Pope. Subs not used: Joyce, Kay, Hornby, Quigley, Vassell, Hardcastle
Booked: Oyeleke
Exeter City: Pym, Sweeney, A. Martin, Croll, Moxey, Boateng (Collins, 70), Tillson (Ogbene, 64), Taylor, Law, L. Martin (O’Shea, 90+1), Stockley. Subs: Hamon, Forte, Jay, Hartridge
Booked: Tillson, Moxey, Stockley
Attendance: 4,615 (350, away)