Goals from Dusan Tadic and Jan Bednarek looked to have Saints on course for a first home league win since November for Mark Hughes' side but Giroud, a 61st-minute substitute, scored two goals either side of Eden Hazard's strike to spare Antonio Conte's side what would have been a sixth defeat in their last eight league matches.

The victory keeps Chelsea's slim hopes of salvaging a top-four finish alive, while Southampton remain in the relegation zone.

After a stale opening 20 minutes, Southampton sparked the match into life when some neat play down the left released Ryan Bertrand.

The former Chelsea left-back powered past Cesar Azpilicueta into the box and squared for Tadic to sidefoot home for his first league goal since December.

Saints then began to take control of the match, although Chelsea spurned a good chance to level near the half-hour mark when Davide Zappacosta nodded the ball across the area but Alvaro Morata's tame header looped comfortably over the bar.

Chelsea full-back Marcos Alonso was fortunate to remain on the field when his studs came down on the back of Shane Long's ankle, but referee Mike Dean took no action despite being close to the incident.

The home side maintained the upper hand at the start of the second half. Long was released by a long ball over the top. His first touch allowed two defenders to catch him, but he twisted clear and forced an acrobatic save from Thibaut Courtois after the Republic of Ireland forward's shot hit his standing leg.

But it didn't take long for the home side to make their greater drive and creativity count. Ward-Prowse whipped in a typically inviting delivery from the right flank on the hour mark and Bednarek, making his first league start for the Saints, arrived unmarked at the far post to coolly guide it low past Courtois.

Giroud replaced the ineffectual Morata and, 10 minutes later, the France international gave his side hope when he leapt to head Alonso's cross from deep for only his second goal for Chelsea since joining them from Arsenal in January.

That goal was quickly followed by the equaliser, with Willian's low cross from the left finding Hazard, who was able to take a touch before firing home from inside the area to spare his side's blushes.

And, with Southampton on the ropes after seeing their lead evaporate so quickly, Giroud delivered the killer blow. Saints failed to clear their lines as Chelsea applied the pressure and the ball fell for Giroud to fire home a low drive from the edge of the box.

Chelsea next face a challenging trip to Burnley in the league, while Southampton travel to Leicester before the two sides meet again in an FA Cup semifinal at Wembley on April 22.