Manchester United striker Wayne Rooney believes Arsenal could still win the Premier League this season.
Rooney says the fifth-placed Gunners have the ability to produce a sequence that could threaten the two Manchester clubs' hopes of securing the title.
"I certainly wouldn't write Arsenal off, they're capable of going on a big run," he told the BBC. "You can't write them or Chelsea off.
"It's great for the league that there are so many teams that can win it."
United face Arsenal in the Premier League at Emirates Stadium on Sunday with Arsene Wenger's men 15 points behind leaders Manchester City with 17 games remaining.
Arsenal go into the game with memories of the 8-2 defeat by Sir Alex Ferguson's men at Old Trafford in August fresh in their minds, but Rooney is impressed with the way they have responded since that embarrassment.
"To beat Arsenal 8-2 with the players and history they've got, it was certainly a great result, and a shock as we didn't expect it," he said.
"But since then, they've gone on a great run and any team under Arsene Wenger is capable of that.
"It wasn't just that result. It was their start to the season. They weren't getting the results they needed and a lot was said about them."
Arsenal recovered from the Old Trafford defeat by gathering 28 points out of a possible 36 in the Premier League until the 1-0 defeat by Manchester City on 18 December.
Rooney believes Arsenal have been inspired by the talents of Robin van Persie and Aaron Ramsey.
Van Persie has scored 18 Premier League goals this season, equalling his best-ever total in a league campaign, while Wales skipper Ramsey has caught the eye with a series of confident performances in midfield.
"Van Persie is scoring a lot of goals, playing really well, and he'll be the biggest threat for Arsenal on Sunday," said Rooney. "He and Ramsey are certainly the two standing out for them this season."
Rooney scored a hat-trick in the 8-2 win in August, with his final goal coming from the penalty spot. His recent penalty record is patchy, with four misses from his last eight, but he insists that he will step up should United be awarded a spot-kick.
"Of course I'll still take the penalties," he said. "These things happen, sometimes you miss, it's not nice to miss but I'm not worried about it."