Chelsea host Arsenal at Stamford Bridge in a 12.30 kick-off on Sunday, and Merson is predicting a 3-0 victory.
He said: "When they are losing too many of them just go completely and utterly missing. The shape goes out of the window and if they let in the first goal it could be anything.
"People are saying to me 'what a good result against Bournemouth' but if you could have handpicked any team to play last week it was Bournemouth.
"If Arsenal score first it will be a very interesting match but I don't think they will."
It is a big test for an Arsenal team which have a brittle confidence, as seen in their recent 4-0 defeat by Liverpool.
Gooners will still be haunted by the 6-0 loss at Stamford Bridge two seasons ago, Arsene Wenger's ill-fated 1,000th game in charge.
The two teams have met once already this season in the Community Shield, a 1-1 draw which Arsenal won on penalties.
Chelsea will be out to avenge that, but most importantly get one back for the FA Cup final defeat back in May.