Welbeck has been struggling with an unspecified injury but the England striker is ready to go at Wembley, if he is picked, although the Gunners have problems in goal.
First-choice keeper Petr Cech picked up a knock in the win over Everton and he faces a late fitness test, with David Ospina standing by to start the clash.
Wenger said: “Danny Welbeck will be back and we had a few problems with Petr Cech, we’re not sure at the moment because he’s not practiced – I don’t know if he’ll be available.”
Uwe Rosler was sacked by Fleetwood following a 3-0 reverse at Doncaster which condemned Town to a seventh straight defeat in all competitions.
Cambridge interim head coach Joe Dunne was pleased with how his side adapted to beat Grimsby 3-1.
Southend manager Chris Powell led the applause for Jason Demetriou after the right-back scored twice in the 3-1 win against Portsmouth at Roots Hall.
Morecambe boss Jim Bentley was the happier manager after Gregg Wylde's 90th-minute strike earned his side a point in their 1-1 draw with Forest Green.
Manager Gareth Ainsworth described Wycombe's 2-0 win at Cheltenham as a thoroughly professional performance.
Skipper Richard Wood scored the winner just before half time as in-form Rotherham pulled off a 1-0 victory at League One leaders Shrewsbury.