Manchester United are coming into the Manchester derby at Old Trafford on a terrific run of form in both the league and domestic cup competitions.
They are currently fourth in the league table and a win this Saturday will take them to within a point of their city rivals in the standings.
Agbonlahor stressed that Manchester United have not been so good for a while and pointed out that they managed to get results against Manchester City in previous seasons even when they were not at their best.
He warned Guardiola against making any silly decision and urged him to play his best team in the derby as Marcus Rashford in his current form should be a scary prospect for any side.
The former striker said on talkSPORT: “They are in perfect shape
“In previous seasons, when they have not been this good, they still went and played Manchester City and put up a performance.
“Pep can’t be making silly decisions, he has got to play his best side against this United team.
“Kyle Walker has got that speed but this Marcus Rashford is a scare for any defender.”
Manchester City have the second best away record in the Premier League this season, losing just once on the road.