Youssouf Mulumbu will be asked about tweet

Irvine is planning to speak to Mulumbu over a cryptic pre-match tweet which appeared to poke fun at the decision to leave him out of the 18-man squad.

But the Hawthorns head coach, who also defended the decision to leave Silvestre Varela and Sebastian Blanco off the bench, believes Mulumbu will recapture his missing form.

"I thought he started the season really well," said Irvine.

"He was absolutely terrific and then unfortunately he got a hamstring injury while away on international duty and that's knocked him back a bit.

"I've got every faith that Youssouf will come again. He hasn't played so well since he came back from the injury but at the beginning of the season he was one of the first names on the teamsheet."

Mulumbu raised eyebrows by tweeting "In the stand looool...." after finding out he would not be involved.

And Irvine is planning to ask him about his reaction. "We haven't spoken yet, but we will have a chat," said Irvine.

"The fact is that Youssouf joined us on Friday having been away for two weeks (on international duty), so he wasn't really in contention as a result of that.

"We spent time preparing for the game. It would have been very difficult going into the challenges that this game brings without being fully prepared.

"Youssouf joined in a fairly light session on Friday and wasn't around to do all the work that we needed to do in order to try to be in the best condition to go to Chelsea."

Summer signings Varela and Blanco both made the trip to Stamford Bridge but once again neither was included in the matchday 18.

"They were available but I picked a squad that I did because I thought it was the right one," said Irvine.

Midfielder Claudio Yacob now faces a three-match ban after receiving a straight red card for a tackle on Diego Costa.