If in doubt turn to the £106.8m world champion sitting on the bench. It was the equivalent of money shouting through a megaphone when Enzo Fernández entered the fray after 65 minutes of watching Chelsea toil against the side sitting fifth in League Two. Mauricio Pochettino was in no mood to be caught out this early into his time at Stamford Bridge and, hard though AFC Wimbledon fought to upset the odds, a feisty Carabao Cup tie was only going one way once Fernández was on. The Argentina midfielder was never going to miss when he was presented with the chance to score his first goal for Chelsea after a mix-up in the Wimbledon defence with 19 minutes remaining. Fernández was simply too cool, too composed, and Pochettino’s side could finally spy a route into the third round. It had not been a comfortable experience. Wimbledon were awkward throughout, Harry Pell delivering a hilariously niggly performance, and a Chelsea humiliation was on the cards when the visitors took an early lead after being awarded a harsh penalty. Pochettino, who knows he has to bring silverware to Stamford Bridge, was relieved. There was little cohesion from Chelsea, even after Noni Madueke levelled from the spot just before half-time, and the scares continued deep into seven minutes of added time, Ali al-Hamadi twice spurning opportunities to force a shootout. “I’m so proud,” Johnnie Jackson, the Wimbledon manager, said. “I’m just a bit gutted we haven’t pushed them all the way.” There was an experimental lineup from Pochettino, who handed full debuts to Lesley Ugochukwu, Mason Burstow and Diego Moreira, but Chelsea still had plenty of firepower on a bench containing the two most expensive players in the history of English football. Wimbledon, after all, have been known to pull off an upset or two in their time. Perhaps that was why Pochettino had Moisés Caicedo and Fernández sitting amongst the substitutes, just in case Chelsea needed to unleash £221.8m worth of midfield talent. “I think their manager’s hoping he doesn’t have to use them,” Jackson said. “It’s testament to my players that he had to bring them on.” There was nothing complicated about Wimbledon’s approach. Their physicality unsettled Chelsea and Pell relished his role as pantomime villain. The midfielder was a constant pest and there was an inevitability to him being involved in the opening goal. The danger came when Wimbledon pumped a free-kick into the area. Pell leapt into the challenge and soon found himself on the turf. Robert Sánchez had flown off his line and, while Chelsea’s goalkeeper made clean contact with his punch, he was penalised by the referee, Tony Harrison, for catching Pell. Chelsea disagreed with the decision. Pell stayed down for treatment, though he recovered sufficiently to direct a clenched fist at the home supporters as they rained abuse down on him. It all felt worth it once James Tilley blasted the penalty past Sánchez. Pochettino was incandescent. There was a sharp exchange of words with Pell before the game resumed and Chelsea found it difficult to regain their composure at first. The closest they came to an equaliser was when Ian Maatsen saw a deflected effort spin just wide. “It was tough,” Pochettino said. “I am happy with the performance overall. We had players on the bench if they were needed.” The nerves only faded when Madueke wriggled clear on the right and lured Alex Pearce into a risky challenge. It was a clear penalty and Madueke made Pochettino’s half-time speech a little easier by sending Alex Bass the wrong way. Pochettino was proactive, though. Nicolas Jackson came on for Moreira, who struggled on the left, and Chelsea moved the ball with more urgency at the start of the second half. Jackson threatened and Conor Gallagher, wearing the armband, tested Bass. Yet Wimbledon retained a threat on the break and it took a fine block from Axel Disasi to deny al-Hamadi after the substitute outmuscled Marc Cucurella, perhaps making Manchester United think twice about signing the left-back on loan. It was time for Chelsea to turn to Fernández, who soon tested Bass with a curling drive. Wimbledon were wobbling and they cracked when Bass raced out to deal with a pass from Cucurella, struck his clearance against Maatsen and was stranded when the ball ran to Fernández, who delivered swift and decisive punishment from 20 yards out. That should have been that, though Wimbledon kept chasing an equaliser. They could take pride in seeing Pochettino bring Caicedo on to see it out.