The mood of a club can change quickly in the helter-skelter Premier League and while United's League Cup semi-final win over Manchester City and the electrifying form of Wayne Rooney has them on a high, Arsenal need a quick pick-up.
Last weekend's FA Cup defeat at Stoke was a blow and on Wednesday a 0-0 draw at Aston Villa, while on the face of it not a bad result, left Arsene Wenger's side slightly adrift in the title race.
"We want to win our next home game - it is as simple as that," Wenger, whose side face Chelsea and Liverpool in their next two games, told Arsenal's website.
"We go from game to game because if you think too much ahead it is not too good."
Vermaelen's injury means that veteran defender Sol Campbell could be called into action for a third time in a week.
"Sol has not played for six months and just in three days he has had two big games, so I will have to see how he recovers," Wenger said.
United's 3-1 victory over City, for a 4-3 aggregate win, was sealed by a last-gasp header by Rooney who is enjoying the best goal-scoring form of his career at just the right time.
"His control, his leading of the line, his penetration is absolutely fantastic," Ferguson said of the man who is pivotal to United's hopes of a fourth consecutive title."
"I think we need Drogba back, he is a fantastic player," Ancelotti said.
"We did very well in January. I want to thank my players because without the African players we could have had problems but they did very well."
