Manchester United winger Nani views Arsenal as a bigger title threat than Chelsea this season.
The Gunners visit Old Trafford on Monday looking to consolidate top spot in the Barclays Premier League table.
For their part, United know a home win would allow them to jump back to the summit, while retaining a match in hand following the postponement of last week's visit to Blackpool.
It promises to be a feast of football, with Nani believing it represents the acid test of United's trophy ambitions.
"Arsenal are a bigger threat than Chelsea now," he said. "Chelsea have lost a few games and drawn some and their confidence looks a bit low.
"But Arsenal have been winning and being top of the league gives you great confidence."