Danny Mills previews Arsenal's trip to Chelsea
Arsenal beat Premier League leaders Chelsea 3-0 last time out in September before the Blues switched to a 3-4-3 formation.
Antonio Conte's tactical change has worked wonders as Chelsea have lost just one league game since to move nine points cleat at the top.
Arsene Wenger beat Antonio Conte at the Emirates Stadium last time out
And former England defender Mills believes Arsene Wenger will need to play three forwards at Stamford Bridge on Saturday to put pressure on Chelsea's back line.
Mills reckons Arsenal, who lost 2-1 to Watford on Tuesday, need to beat their London rivals to have any hope of catching them in the title race.
"Arsenal, hugely disappointing for them to lose against Watford," Mills told Sky Sports. "If they don't win [against Chelsea] their title hopes are definitely over.
Alexis Sanchez looks absolutely distraught after Arsenal's defeat to Watford
Tue, January 31, 2017
Alexis Sanchez looked absolutely distraught after Arsenal's defeat to Watford
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Arsenal lost 2-1 to Watford on Tuesday
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"I think Arsenal have to be brave in this game. Chelsea have done magnificently well with their new system – at the start of the season they changed to a back three.
"And if I was Arsene Wenger, I'd almost play three up top, very high. Play three up against [Cesar] Azpilicueta, [Gary] Cahill and David Luiz.
"Give them a problem, force them back and make those wing-backs drop back and help out, so it almost ends up with five at the back."