Mikel Arteta said the only reason the centre-back started Wednesday (AEDT) was because a bug circulating through the Arsenal dressing room left Pablo Mari unable to go.
The same issue compelled the manager to remove White in the 55th minute, but Arteta said White should be fit for Saturday's Premier League fixture against Leicester City.
"[Mari] was going to start and he couldn’t – he had a bug, something happened around here," Arteta said. "White wasn’t feeling great in the second half so we decided to take him off
Arteta said that White had been dealing with the same illness the previous few days but did what he could.
White's departure proved fortuitous for Arsenal, as Calum Chambers came on to replace him and headed home the first goal of the game within seconds.
Asked if he had ever had a substitute pay off that quickly, Arteta said "I don't think so."
"I’m so happy in particular for Calum," he said. "He totally deserved it. It was a great moment because it helped us to win the game. He’s someone who deserves the best for who he is as a person and how he behaves as a professional."