Forster silences the stumbling Gunners
Arsenal 0 Southampton 0
An inspired display from Southampton goalkeeper Fraser Forster earned his side a point at Arsenal as the Gunners lost further ground on their Premier League title rivals.
There was talk of this being a revenge mission following Saints' 4-0 win in the reverse fixture on St Stephen's Day but Forster was superb as a string of top-class saves secured a 0-0 draw and a share of the spoils for the visitors.
The 27-year-old was playing just his fourth game after returning from a serious knee injury that had sidelined him for 10 months and his superb performance here means he is yet to concede since coming back into the Southampton side.
His heroics here, most notably from Mesut Ozil and Olivier Giroud, mean Arsenal were the only side in the top six not to win and Arsene Wenger's men have now taken just three points from their last four league outings.
Southampton were without recent acquisition Charlie Austin due to a minor injury and they never looked like snatching a victory to secure a famous double.
Sadio Mane could have punished the Gunners as the tricky forward collected a sloppy pass from Hector Bellerin before charging into Cech's box and shooting tamely at the Arsenal stopper.
Forster dived low to keep out a Giroud header moments later as the game started to truly open up with a little over 30 minutes remaining.
Amazingly, the England goalkeeper pulled off two more saves - keeping out substitute Theo Walcott and Sanchez - before Laurent Koscielny headed over from six yards.
When Forster could not get there he could rely on his team-mates to do the job as James Ward-Prowse was on hand to turn Sanchez's low drive off the line.
Another tip over from a Giroud header and a close-range stop from Sanchez continued Forster's outstanding solo display.