Chelsea F.C. 2–4 Bradford City A.F.C. (2015)

In the 13th minute of the game, Gary Cahill blocked a goal attempt by Gary Liddle with his head, sending it to the corner and giving the away side the first corner kick of the game. Filipe Morais took the corner kick and passed it to Andrew Davies who headed it towards the goal. However, Czech goalkeeper, Petr Čech, blocked the shot, and Chelsea's defenders successfully cleared it. Six minutes later, Oscar attempted to pass the ball to César Azpilicueta so that he could score, but Bradford City captain, Stephen Darby, intercepted the ball and kicked it out of play. Oscar took the corner kick and kicked it towards the box, but Darby headed the ball back in the same direction. Oscar took another corner kick and kicked it towards the goal again. This time though, Cahill volleyed the ball with his left foot and Bradford City conceded the first goal of the game. For the next two minutes, Didier Drogba would attempt two shots on target, however, both were blocked by goalkeeper, Ben Williams. Chelsea dominated possession of the ball from the 23rd minute until the 37th minute, and the two teams spent most of their time during that interval in Bradford City's defensive half. On the 38th minute, Egyptian forward, Mohamed Salah, passed the ball to Ramires as the Brazilian ran through Bradford City's defenders and scored their last goal of the game. Two minutes later, Bradford City were given a free kick after Loïc Rémy committed a foul. Like always, Filipe Morais took the free kick and kicked it towards Davies, who passed it to Jon Stead. Stead scored a screamer from the box and gave Bradford City their first goal of the game. The referees added 2 minutes of injury time to the first half, but nothing happened besides a few missed shots on target and a few free kicks.

Filipe Morais kicked a corner in the 53rd minute, and James Hansen tried to head it in, but it was blocked by Čech. Following the save by Čech, Mourinho came off the sidelines to go to edge of his technical area so that he could yell instructions to his players after they had committed multiple errors. Near the end of the 53rd minute, James Meredith crossed the ball to the outside of the box, where it found Filipe Morais who missed an attempt and smashed the ball over the crossbar. On the 57th minute, Oscar missed a potential goal from 30 yards out as the ball went out to the right of Bradford's goalpost, but it deflected off Darby, giving Chelsea a free kick. During a corner kick in the 66th minute, Mikel and Knott's heads collided with each other, getting Mikel injured and delaying the game. Mikel was walked off the pitch by Chelsea's medical staff and subbed off for Cesc Fàbregas in the 70th minute. Mourinho also subbed off Mo Salah for Willian. On the 71st minute, Drogba was fouled by Davies when the Englishman's arm blocked the Ivorian's face as they were competing for the ball. The referee awarded Chelsea a free kick because of Davies' foul and Drogba almost headed the ball into the net, but Williams saved it. In the 75th minute, Morais scored an unexpected equaliser after Meredith's throw-in to bring the game level 2–2. Immediately after the goal, Mourinho subbed off Rémy for Belgian attacking midfielder, Eden Hazard, so that Chelsea would have a better chance of scoring a winner. Hazard, Drogba, Willian, and Fàbregas all attempted to score inside the box for the next three minutes, but they had no space to score and Ben Williams caught to ball to reset the game. In the 80th minute, Phil Parkinson made his first substitution of the game, and subbed off Billy Knott for Mark Yeates. Two minutes later, Jon Stead assisted Andy Halliday as he would score the decisive winner which would send Bradford City to the next round. Chelsea had multiple chances to equal the score during the rest of the game: Drogba's missed header in the 83rd minute, Kurt Zouma's shot in the 85th minute which flew into the stands, and Willian's missed shot in the 2nd minute of stoppage time. Parkinson made his two last substitutions before stoppage time began, subbing off Halliday for Christopher Routis in the 87th minute, and subbing off Morais for Billy Clarke in the 89th minute, after the Portuguese player got a hamstring injury. Despite the fact that Clarke and Darby were each given yellow cards during stoppage, Chelsea couldn't score after both fouls or during the 7 minutes of stoppage time. Mark Yeates sealed the deal for Bradford City in the 94th minute by chipping the ball around Petr Čech to bring the final score to 2–4. The match was slightly delayed before the final whistle as Zouma was carried out of the pitch after an injury.

Because of that win, Bradford City progressed to the Fifth Round, where they would play against another Premier League club with Sunderland. They won the game in their home stadium by a score of 2–0,[24] and reached the Quarter-finals. They wouldn't make a trip to Wembley Stadium though, as they lost 3–0 away to Reading after a replay, ending their FA Cup run.[25] It was also their first quarter-final appearance in the FA Cup since the 1975–76 season. Bradford City would end up finishing 7th in League One, just narrowly missing out on the promotion play-offs by 4 points. They weren't playing in any other competitions at the time, as they were knocked out of the EFL Trophy and EFL Cup back in September.[26][27]

Chelsea did not let that upset affect the rest of their season. Three days after the upset, they would win their second-leg tie against Liverpool in the EFL Cup semi-finals by a score of 1–0 thanks to an extra time goal by Branislav Ivanović, allowing them to win 2–1 on aggregate.[28] They would then go on and win the final 2–0 against London rivals, Tottenham Hotspur.[29] They would also stay first in the Premier League for the rest of the season, and secure their 5th English title with 3 games to spare, after a 1–0 win against Crystal Palace.[30] However, their hopes of progressing past the Round of 16 in the UEFA Champions League ended after they tied the second leg 2–2 at the Bridge, bringing the aggregate score to 3–3, allowing Paris Saint-Germain to go to the next round on away goals.[31] Bradford were the only away side to win at Chelsea all season.[23]