It was a night to forget for Mansfield keeper Alan Marriott at the One Call Stadium tonight as, despite Stags twice going ahead, he twice conceded penalties and also pushed a low cross against Lee Beevers for an own goal as City stole a 3-2 win in stoppage time.
Mansfield trialist Calvin Andrew had scored one and helped set up another to twice edge the Football League new boys ahead, but the night eventually belonged to the Sky Blues.
In very warm temperatures, the game was played at a sedate pace at times, but there were plenty of chances at both ends.
Stags had two more trialists on the bench in Brent McGrath and Eddie Gnahore.
A free agent, McGrath (22) has a full international cap for Australia and four U20 caps. His last club was Danish Superleague side Brondby IF and in a cameo appearance for the last 14 minutes went close once but had little real chance to impress.
Gnahore (19) is a former Birmingham City midfielder and didn’t get on in the end.
Coventry sent out a young side missing almost all their bigger names and including three overseas trialists.
Mansfield almost took a third minute lead when Dyer nodded on a long Beevers throw from the right, the ball sailing towards Dempster, who missed the target with a six yard header.
But Portuguese trialist Martins spurned an even better chance four minutes later.
He began the move, spreading the ball to Baker to his right. Baker then curled the perfect return into his path, putting him one-on-one with Marriott only to sky his finish over the bar.
Marriott then had two saves to make in as many minutes as Stags were twice caught square at the back, first blocking a low Manset effort, then denying Wilson with a similar stop.
Daniel wasn’t far wide with the deftest of touches from a low Jennings cross, then Murray’s header was too high from a right wing Clucas cross.
McGuire then guided a header over from seven yards, from a powerful Beevers cross, the midfielder doing well to cushion it but unable to get it on target.
However, the Stags did draw first blood through Andrew on 23 minutes. There seemed little danger when Dyer’s flick reached Andrew on the right of the box with Finch in close attendance behind him.
But Andrew was strong and forced a slip from Finch before curling a magnificent finish beyond the reach of keeper Burge and under the far angle.
Martins should have done better on 31 minutes when Christie sent a cross right onto his head six yards from goal and central, only for the trialist to glance his header wide.
Baker almost levelled the game four minutes later with a fine curling effort from 25 yards, which beat Marriott but sailed narrowly wide.
At the other end Clucas was just too high with a flicked header from a Jennings free kick.
The Sky Blues were finally level from the penalty spot on 37 minutes.
A great burst of pace from Wilson took him into the box and one-on-one with Marriott. Wilson tried to round Marriott, inviting the challenge, which brought him down.
Marriott guessed the right direction for Baker’s kick, but couldn’t get down quickly enough to keep it out.
A minute later Manset headed a Baker corner over the bar, then Marriott had to block a stinging Baker shot, after the City skipper’s one-two with Manset.
The final action of the first half saw Andrew send a free header wide from six yards from Jennings ball in.
Martins was well wide with a header for the first goal attempt of the second half.
But on 49 minutes Clucas restored the home side’s lead.
Andrew leapt well to head on a long Marriott kick and Clucas, still with plenty to do, burst forward, drew the keeper and slotted it low to his right inside the post for a calm finish.
Marriott was relieved to see a deflected Manset shot loop wide of his post.
Then Dyer wasted a great opening on 55 minutes. Jennings’ corner was kept in play at the far post by McCombe, who turned it back towards Dyer, whose finish rocketed high into the stand.
Andrew was up again well with a late run to get on the end of a Jennings corner but could not get over his header and again the ball found the South Stand.
A long bowl out from Burge was returned towards Clucas, who got past Azille-Moore before seeing Burge get down to block his measured finish.
City drew level again thanks to an own goal from Beevers.
Wilson got down the right and crossed hard and low. Marriott tried to cut the ball out at the near post but succeeded only in pushing the ball against the legs of a helpless Beevers and into the net.
Christie tested Marriott from 25 yards, but he was firmly behind the effort.
Clucas went past City first teamer Christie on 78 minutes and Christie grabbed hold of his shirt and wouldn’t let go.
The referee blew, but Clucas reacted angrily and shoved Christie in the chest. Players from both sides raced in for a session of pushing, shoving and posturing before it all calmed down and Christie and Clucas were booked.
Howell sent McGrath into the box for his first real taste of the action as a 76th minute sub, and he came inside to curl a decent effort just wide of the far post.
Then Howell was close with a low first time effort from a lay-off by Jennings.
Haynes had to make a superb goal line clearance on 88 minutes after defender Dempster had superbly lifted the ball over Burge amid a scramble, and seconds later it was Dempster again who came close as he guided a header over from Jennings’ left wing cross.
In the third minute of stoppage time, the visitors struck the fatal blow.
Wilson, still full of pace and life despite the heat, raced into the box and tried to sidestep the keeper, Marriott bringing him down.
Baker again took responsibility and lashed a powerful spot kick past Marriott to win it.
STAGS: Marriott, Beevers, Jennings, Dempster, McCombe (Sutton 76), Murray (Howell 69), Dyer (McGrath 76), Clucas, Daniel (Meikle 69), Andrew (Stevenson 69), McGuire. Subs not used: Speight, Tafazolli, Black, Gnahore, Clements.
COVENTRY: Burge, Christie, Haynes, Barton, Finch, Orozco (Azille-Moore ht), Daniels, Baker, Manset (Maund 84), Wilson, Martins (Garner 64). Sub not used: Gott.
REFEREE: Gary Sutton of Lincs.
ATTENDANCE: 1,072 (121 away).