Rumoured Manchester United target Sadio Mane was forced off with suspected concussion as Southampton went a third game without victory in a 0-0 draw at promoted Watford on Sunday.

Southampton manager Ronald Koeman has declared that Mane is not for sale amid reports linking him with United, but the Senegalese flier lasted only 25 minutes at Vicarage Road before the after-effects of a collision with Watford goalkeeper Heurelho Gomes brought an abrupt end to his afternoon.

The best chance of a poor game fell to Watford midfielder Etienne Capoue, but he headed over the bar from close range in the second half to leave both teams still seeking a first win of the Premier League campaign.

Held 1-1 by Danish side FC Midtjylland in the first leg of their Europa League play-off on Thursday, Southampton have not won away from home in the league since February, but they did at least record a first clean sheet in nine league outings.

The first half was low on incident, with Watford winger Ikechi Anya the player who looked most likely to provide a breakthrough.

Twice he put dangerous crosses into the Southampton box, but no-one got on the end of the first chance and Odion Ighalo failed to apply a decisive touch to the second.

Southampton's efforts to find a breakthrough were compromised when Mane was forced to leave the fray.

But his replacement, Shane Long, almost unlocked the home defence with a cross that Graziano Pelle headed wide.

Alessandro Diamanti came on for Watford at half-time to make his debut following his arrival on loan from Guangzhou Evergrande, but strike partner Troy Deeney spurned a chance to tee him up, instead seeing a shot blocked by Steven Caulker.

At the other end, a rising effort from Pelle was tipped over by Gomes.

Watford should have gone in front in the 67th minute when Deeney's flick-on at a corner found Capoue two yards out, but the former Tottenham Hotspur midfielder somehow contrived to head over at the back post.

In reply, Victor Wanyama worked Gomes from 25 yards, while Cedric Soares fired narrowly over.