Substitutes Brennan Johnson and Djed Spence scored in the final two minutes of this exhilarating Carabao Cup tie to enable Tottenham Hotspur to recover from Brandon Thomas-Asante’s deserved goal for Coventry City to sneak through to the fourth round. At least that is one route to a trophy salvaged for Ange Postecoglou. Penalties did for Mark Robins’s team when they lost the Championship playoff final to Luton Town 16 months ago and the FA Cup semi-final to Manchester United last season and they looked set for another trial from 12 yards until Spence, sent in by Dejan Kulusevski, stabbed home from close range. Yet until the introduction of James Maddison, Son Heung-Min and Kulusevski, Spurs had been largely outplayed – and certainly out-fought – by the spirited Championship side. Then, in stoppage time, Rodrigo Bentancur played Johnson in on goal and the Wales winger, abused online after his efforts in the North London derby defeat on Sunday that he deleted his Instagram account, slipped in the winning goal. Both teams may have made middling starts to their respective league campaigns, but the pressure was clearly more on Spurs. Few neutrals mind a manager who shows ambition and shoots from the hip, and Postecoglou won many an impartial heart by his conviction that he “always wins things in my second year”. This he may have done in Australia, Japan and Scotland, where he won the title in his second seasons in charge, but the Premier League is a completely different beast. All of which suggests he would need to win a cup, a feat Spurs haven’t managed since 2008, to maintain his successful second-season streak, and the Carabao Cup offers an easier target than the FA Cup or Europa League. So it appeared something of a risk for Postecoglou to make eight changes to the team that lost 1-0 to Arsenal on Sunday. Coventry, after all their heroics over the past 18 months, also made seven, but Robins’s team appeared far more up for this cup in the first period at least. It is 11 years since these teams last met, and Spurs had never previously visited this stadium, but Coventry were in no mood to offer undue hospitality. This was their third game in this competition already, after 1-0 wins over Bristol City and Oxford United, and they sniffed unease in the Spurs ranks straight from kick-off. When Fraser Forster played the ball out to Lucas Bergvall, on his first start for Spurs, Jack Rudoni was quick to pounce on the loose touch. The former England goalkeeper had to palm the powerful cross-shot behind for a corner with 45 seconds on the clock. The portents did not get better for the visiting side, who had made wholesale changes when going out at their first hurdle of this competition 12 months ago, losing on penalties to Fulham, when Wilson Odobert went down injured, and had to be replaced by Brennan Johnson. It was down that flank, where Archie Gray was making his first competitive start for Spurs since his £30m move from Leeds, that Coventry came even closer to going ahead on two occasions shortly before the interval. The excellent crossing of the left-back Jake Bidwell troubled Spurs and, from one expert delivery, Rudoni arrived late and struck a half-volley that Forster saved with his legs. Moments later, Norman Bassette got down the inside-left channel to dispatch a superb shot that Forster tipped over; not that the referee Darren England credited him, awarding a goal kick. While Coventry could be satisfied with their first-half efforts, Spurs were booed off for theirs. Postecoglou replaced Destiny Udogie with the lesser-spotted Spence, and Johnson had a shot deflected behind, but still it was Coventry who kept coming. Again, it was down that inside-left channel that Coventry probed, with Thomas-Asante having one shot blocked behind, then the Belgian teenager Bassette, a constant menace, forced a save from Forster. The decently sized home crowd sensed another upset was on. Their major cup memories against Premier League opposition last season came at Molineux, against Wolves, and Wembley, against Manchester United, but this time the metaphorical lid came off the CBS Arena when, immediately after James Maddison and Son Heung-Min were introduced, Bassette crossed and Thomas-Asante calmly sidefooted home. As both teams strengthened through their substitutions, it was still Coventry who came closest to scoring again until that late double blow. Ellis Simms, who scored six goals in that FA Cup run, came on and headed one cross Bidwell just wide before driving a low cross-shot that Ephron Mason-Clark so nearly slid home. Comments on this report will open shortly