Southampton beat Wayne Rooney's Birmingham City in Championship

The hosts took the lead at St Mary’s when Armstrong’s cross was powered home by Harwood-Bellis to set them on their way.

Kamaldeen Suleman then set up Alcaraz to double the Saints lead in a dominant first half display.

Jay Stansfield gave the midlands side hope in the second half but Armstrong sealed the victory when he fired home late on.

Russell Martin made four changes to the side that drew 2-2 with Preston North End with Taylor Harwood-Bellis, Stuart Armstrong, Kamaldeen Sulemana, and Carlos Alcaraz all coming in.

James Bree kept his place in the Saints line-up despite Ryan Manning being available again after his suspension.

Saints made a bright start and took the lead in the opening 10 minutes when Armstrong crossed for Harwood-Bellis to power a header past John Ruddy in the Birmingham goal.

It is exactly what the hosts deserved after a dominant start with the visitors camped inside their own half for much of the opening stages.

Birmingham had lost their last four away games going into the fixture and it did not look like their luck would change any time soon.

Saints made it 2-0 after 22 minutes, when Kamaldeen burst down the left-hand side before he laid the ball on a plate for Alcaraz to double the advantage.

It was the Argentine's first goal of the season and it had put Southampton well on their way to making it six matches unbeaten.

The away side felt they should have had a penalty soon after when Oliver Burke was clattered by Gavin Bazunu but the referee was not moved by the appeals.

Harwood-Bellis and A Armstrong both had opportunities at the end of the half but their efforts drifted narrowly off target.

It had been a dominant first half display by Saints and Rooney would have known that his side had to improve after the break to get anything out of the game.

Perhaps one of the main positives for the Southampton boss Martin would have been that his side did not look likely to concede, despite only keeping one clean sheet in the last 27 home league games.

A Armstrong, who had scored five goals in his last three Championship fixtures against Birmingham City, glanced a header wide just after half time.

Rooney turned to his bench with just over half an hour remaining and his decision immediately paid dividends.

Within seconds of coming on, Stansfield pounced on a mistake by Kyle Walker-Peters before curling the ball into the top corner to give the visitors hope.

That goal seemed to give the away side confidence and Lukas Jutkiewicz suddenly became more of a threat as he tested Bazunu in the Saints goal with a firm strike.

But A Armstrong sealed the three points with just five minutes remaining when he fired the ball low into the net after Samuel Edozie's knockdown.

The result moves Saints up to fourth in the Championship table before Preston North End below them play this afternoon.

Saints: Bazunu; Walker-Peters, Harwood-Bellis, Bednarek, Bnree; Downes, Smallbone (Charles, 82), S Armstrong (Edozie, 82); A Armstrong, Kamaldeen (Fraser, 76), Alcaraz (Aribo, 69)

Unused subs: McCarthy, Holgate, Manning, Amo-Ameyaw, Mara

Birmingham City: Ruddy; Drameh, Sanderson, Aiwu (Roberts, 76), Longelo; Bielik (Gardner, 69), Sunjic; Burke (Hogan, 69), James, Dembele (Stansfield, 57); Jutkiewicz (Miyoshi, 76)

Unused subs: Etheridge, Laird, Long, Khela.

Booked: Aiwu, Gardner, James, Stansfield.

Referee: David Webb

Attendance: 28,924

Goals: Harwood-Bellis 9'. Assist: A Armstrong

Alcaraz 22'. Assist: Kamaldeen

Stansfield 58'.

A Armstrong 86'. Assist: Edozie