Wycombe gave debuts to new signings Jordan Obita and Nnamdi Ofoborh, while striker Sam Cosgrove began life at Birmingham on the bench, following his arrival from Aberdeen last weekend.

Beneath a deluge, the early stages largely passed both teams by, although Blues goalkeeper Neil Etheridge did have one nervous moment when he misjudged a bouncing ball in his own area.

Lukas Jutkiewicz had the first shot of real note halfway through the first half, as his powerful strike on the turn from 25 yards was beaten away by Allsop.

The hosts then came close themselves soon after, as Fred Onyedinma's corner was nodded back across by Ryan Tafazolli and Admiral Muskwe's header was helped over by Etheridge.

The match was just starting to warm up by the half-hour mark, with Ivan Sunjic sending a well-struck half-volley just wide for the Blues.

The Croatian then sent another warning shot across Wycombe's bows just off target, after the Chairboys had made a mess of getting the ball away from their own area.

Etheridge then came to his side's rescue again, as he reacted superbly to keep out Uche Ikpeazu's deflected shot, as Tafazolli had got his head to another Onyedinma set-piece.

That helped keep the scoreline blank at half-time, while a terrific one-handed save from Allsop prevented the deadlock from being broken eight minutes after the restart, as he sprung to his left to keep out Mikel San Jose's header.

The standard drifted back into the scrappy fare that was served up in the opening stages, with the two goalkeepers becoming bystanders once again.

That finally changed after 74 minutes when Jeremie Bela's brilliant cross from the right was met by Maxime Colin, only for Allsop to somehow claw away his header from point-blank range.

Birmingham lost Roberts to a red card with three minutes left after he hacked down Onyedinma as he threatened to sprint away from him.

There was still time for one more chance for the Blues, but Gary Gardner could only flick a header from Bela's corner over the top.