Manchester United captain Roy Keane believes his side's Premier League title hopes will be over if they lose again this season.
The champions are five points behind leaders Arsenal and Keane cannot see a repeat of what happened last season when Alex Ferguson's team overhauled the Gunners in the run-in by going 18 games unbeaten.
"We fell behind last year and put ourselves under a lot of pressure but if I am being honest I can't see Arsenal slipping up like they did last year," Keane told the Manchester Evening News on Thursday.
"Of course I am worried that we have lost five times and Arsenal haven't lost at all," the midfielder added. "If you want to win any championship, the fewer games you lose the better.
"We are just putting ourselves under so much pressure. The gap that is between us now must not get any wider."
Keane feels United, who have conceded 10 goals in their past four games, may be even more vulnerable defensively as they attempt to close the gap.
"Basically, we are putting ourselves under a lot of pressure, especially when we are playing the top teams like Liverpool, Arsenal and Chelsea, we have to be winning these matches," said Keane.
"That leaves you vulnerable at the back because you have to go gung-ho in attack.
"We did it last year and, hopefully, it will be the same scenario this season."
United's next game is at home to Leeds United on Saturday, when Arsenal travel to third-placed Chelsea.