Was this the most brutal substitution in recent football history?

It is certainly the most ruthless decision Sonia Bompastor has made in her time as Chelsea head coach and, probably, her career.

After just 12 minutes, she decided Kadeisha Buchanan was being exposed so badly by Manchester City striker Khadija “Bunny” Shaw that she had to take her off.

Chelsea’s players looked over in bemusement as the substitute board went up. Katie McCabe gave the bench a stare that read: “This better not be me.”

Buchanan jogged off as her number went up before going straight down the tunnel as Veerle Buurman came on in her place. Bompastor had attempted brief words of comfort, but her defender, understandably, showed little interest.

The official line from Bompastor after the game was that Buchanan had taken a knock to the head in training but admitted the change was tactical.

“She was fine after the training session, she was fine in the evening and we assessed her again this morning and everything was fine,” Bompastor said.

“I had this information on what happened yesterday and I just felt, watching her from the beginning of the game, she was not herself. I took the responsibility to make this substitution. I was almost forced to do that because, I know my player, and I know she was not right in the game.”

It was one of those decisions that was high risk, high reward. For Bompastor, it paid off spectacularly.

Buurman put in a player-of-the-match performance to keep Shaw at bay and help Chelsea to a crucial victory – one which moved them above City at the top of the table. Sandy Baltimore’s fierce strike just before half-time proved to be the difference, but the game turned following Buurman’s introduction.

“I think you have to be brave to make that decision in that moment because bringing a player [on] in that moment in the game, it’s a risk,” Bompastor said.

“It didn’t happen many times to me in my experience. We had a good conversation with Veerle. I believe in her, she’s a really good player. She had a really good performance.”

Asked whether she had spoken to Buchanan after the game, Bompastor said: “I just told her a few words [as she came off]. I’ll explain myself to her.

“I think my assistant coach Camille has probably done that already. I think that everything will be fine. I always have a good relationship with all my players, I always give them clarity, I’m always direct and honest.”

City could have been 2-0 ahead in the first 10 minutes and endured a wasteful afternoon in front of goal. They had chances later in the game, with Lauren Hemp somehow missing from two yards out. Chelsea were just as frustrating in the final third but capitalised when Baltimore was given time and space to fire into the top corner from just outside the box.

City made life more difficult for themselves when goalkeeper Ayaka Yamashita was shown a straight red card for denying a goal-scoring opportunity.

Alyssa Thompson was a long way from goal when Yamashita flew into her, and there did look to be covering defenders, but it was a foolish and unnecessary challenge.

“Of course it’s always affecting when you’re one player down,” City head coach Andree Jeglertz said. “But that’s not why we lost the game. I think it’s small details. There was a lot of situations, a lot of battles in the game. We had a couple of great opportunities where we don’t manage to score.”

This result could prove crucial in what feels like a two-horse title race. Chelsea are now the only unbeaten side in the Women’s Super League but are just one point ahead of reigning champions City. This was a game decided by tight margins and one ruthless decision.