Slaven Bilic hailed two-goal Charlie Austin as a class act but admitted he cannot guarantee him a start as West Brom came from behind to beat Birmingham 3-2 at St. Andrew's.

Substitute Austin scored with his first touch of the ball in the 73rd minute and grabbed the winner eight minutes later to make it six goals in five games and extend West Brom's unbeaten run to 12 matches.

Birmingham led at the start of both halves through headers from Lukas Jutkiewicz and Harlee Dean after three minutes and 47 respectively, but Grady Diangana levelled in the 10th minute before Austin turned the game.

"The first goal is pure class, the second goal, some may say it was an easy finish, but his movement to get away from the defender is class," said head coach Bilic.

"The ball was good and he doesn't miss those chances.

"It is great when you strikers are scoring. Charlie has scored six in five, Hal is scoring goals, and you can't beat that."

Austin is playing second fiddle to Hal Robson-Kanu and Bilic suggests the former Southampton man must continue to be patient.

"I am sure he would rather start but it's great to have that kind of a player," said the Baggies boss.

"That is what Hal was doing for a few games as well. He came off the bench and scored against Stoke, Middlesbrough away and a few games.

"Now Hal has got his chance and deserved it. But it is impossible to play with one striker and in every club you have to share it around."

West Brom twice came from behind and while Bilic would prefer his team to be in front, he says his players have the belief to retrieve points from a losing position.

"I would rather have the option of taking the lead than to be losing," added the Croatian.

"That belief comes from recent games, so you have confidence, you don't have to rush, just play your football, and this game will also help."

West Brom's only disappointment was losing winger Diangana to a hamstring injury.

"He is having a scan. He pulled it but it's not like a big one," said Bilic.

Birmingham boss Pep Clotet admitted Austin made the difference.

"The last few games Austin has been very effective coming on," said Clotet.

"When it comes goalscoring, I think West Brom made that difference.

"They had three shots on target and they scored three goals – Austin came on and had that cutting edge that made a little bit of difference."

Birmingham had only themselves to blame after Kristian Pedersen and Jeremie Bela missed chances.

"I think Kristian's was a clear chance and Bela probably in the end as well," said Clotet.

"Despite when they turned the game and are winning 2-3 I think we did enough to try to get back."

Clotet believes he could not have got any more from his team.

"Our players put everything they had into getting the points," the Spaniard added.

"I did see a Birmingham side who played for the shirt, played for the fans and bounced back from Wednesday. I am proud of the lads and their effort.

"There are so many positives that help us to grow and keep going.

"Slowly week by week, season by season reduce the distance there was today."