Several eagle-eyed football fans noticed that Middlesbrough striker David Strelec was wearing a different shirt to his teammates.Boro faced Birmingham City in the Monday night Championship clash and left St Andrews with a 3-1 win, but the forward had a change in shirt sponsor on his shirt to the rest of his teammates.Strelec’s shirt sponsor was slightly differentGettyHe had ‘Utilita’ on the front of his shirt, while every other Middlesbrough player had ‘Unibet’ on their kits.This is believed to be an Under-21s shirt due to rules on gambling companies on the front of shirts in the youth levels.So, it looks to have been a classic wardrobe malfunction.Taking to X, formerly known as Twitter, one fan said: “Can we keep Strelec in the Utilita shirt?”Another added: “The main question for me is why Strelec was wearing a different top to everyone else.”And one more said: “Strelec wearing an U21 shirt?”The Slovakian international scored Boro’s crucial third in the 60th minute to move Kim Hellberg’s side four points clear of Millwall in third.Big nightDespite the wardrobe malfunction, Boro produced a great display to win 3-1.After Millwall won 2-0 over Preston North End at the weekend, the gap between second and third was cut to just one point.Middlesbrough were also in a bit of a sticky path of form, failing to win any of their last three, including draws against relegation-threatened Leicester City and Oxford United.That was only Strelec’s fourth goal since joining Boro, so perhaps he should wear that shirt all of the timeBut Hellberg’s side made the perfect start as Newcastle United loanee Matt Targett opened the scoring in the 13th minute.The left-back doubled his and Boro’s tally 13 minutes later with a composed finish from Hayden Hackney’s pass inside the area.That had Boro cruising at half time, but Marvin Ducksch scored a minute into the second half to potentially trigger some nerves for the visitors.But Strelec got on the end of a Luke Ayling cross to power home a header and wrap up three huge points.Commenting on Middlesbrough’s performance, manager Kim Hellberg told talkSPORT: “It was a big win. This is a tough place to come to. They’ve lost once in the last two seasons.“They are a good side, well coached, and they have a lot of good players, so we knew this was going to be a tough one.Matt Targett was at the double for Boro in the first halfGetty“I am very pleased with how we handled it. They started strong in the first ten minutes, and then, we were brilliant, especially in our pressing.“The second half becomes more about defending and I think we did them very well.”Boro face QPR on Sunday as they look to end their Premier League exile which has lasted nine years.