Alex Baumjohann, who swung in a sublime ball for Oriol Riera to open the scoring, looked crestfallen when he was taken off midway through the first half at a rain-soaked ANZ Stadium on Saturday night.

It was all Wanderers in the 20th edition of the derby until a brain fade by Janjetovic in the 26th minute saw the keeper race well out of his area and handle the ball, earning an instant dismissal.

Babbel raised eyebrows when he took off the veteran German in response to the send off, and there will be questions about his tactics after Western Sydney went on to lose 3-1.

"Alex is a fantastic player but his best quality is forward," the coach told Fox Sports before the restart.

"If you’re one man less you have to think more defensively-wise. This is not his biggest strength. 

"It was a very hard decision – I feel very sad for him but I have to make a decision and I hope the players can do what I expect from them and we get a result."

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But the 10-man Wanderers couldn't hold out the Sky Blues who equalised from three set pieces. Skipper Alex Brosque became the fixture's highest scorer with his fifith derby goal before Siem De Jong fired home from the edge of the box in the 57th minute and substitute Jacob Tratt's bullet header on debut sealed the result in the 81st minute.