Defeat left them 19th, six points above the Sky Bet Championship relegation zone, but Karanka remains confident.

"I've never been concerned, even when we lost 4-0 to Derby (in December)," said Karanka, who is close to signing West Brom midfielder Rekeem Harper on loan.

"This group of players deserve to be much higher in the table. We need to do a lot of things to win games and on the other hand we have lost games we didn't deserve to lose.

"With the confidence and commitment we are a different team than we were two weeks ago.

"In 10 games played in the same way, maybe three or four we would have won and another six we would have drawn.

"To win the game we have to be perfect but even being better than the opponent this time we don't have a point.

"We played with some risk as our defenders were really high and we didn't arrive to press them at the right time. The one time we didn't arrive when we had to they scored."

After an uninspiring first half where Alan Browne curled wide and goalkeeper Daniel Iversen saved from Ivan Sanchez, Preston took control after the break.

Brad Potts hit a post for the visitors five minutes after the restart and then forced Neil Etheridge into a fine stop a minute later.

But Sinclair grabbed the winner after 61 minutes when Brighton loanee Jayson Molumby slipped him in and the former Aston Villa striker drilled in his eighth goal of the season.

Birmingham's response was limited and Jonathan Leko's shot which flew wide in stoppage time was their best chance.

It lifted North End to 10th in the table after a fourth win in six league games and they are seven points adrift of the play-off places.

Boss Alex Neil said: "We've had a bit of a transitional season which was always going to come because of contracts and different things.

"To come and win in the manner we did, be 10th and a bit outside the play-offs, I think we've done pretty well.

"Hopefully this year, but certainly next year, is going to be a big year for us.

"We spoke about a few things at half-time about what we could do better and the 20 minutes after half-time won us the match.

"If you look across the match we had the best opportunities, we were the more threatening team and we deserved to win. The first goal at this level is crucial."