Arsene Wenger feared Danny Welbeck might have lost his edge after 20 months fighting two knee injuries.
Welbeck fired his first goals since April as Arsenal thumped Southampton 5-0 in the FA Cup, with Theo Walcott also scoring a hat-trick at St Mary's.
The forward had only just beaten knee ligament trouble when he suffered cartilage problems in late April, but he flourished on the south coast on Saturday to banish his injury worries.
Gunners boss Wenger hailed the 26-year-old's resolve in fending off not one but two long-term knee blows to move back towards top form.