Seven second-half goals helped Arsenal to an 8-0 thrashing of Viking in Friday's friendly in Norway.
Santi Cazorla saw a penalty saved by goalkeeper Iven Austbo after just four minutes, but Arsene Wenger's side responded emphatically to record a third pre-season win in a row.
Theo Walcott and Campbell both struck from close range before the hour mark before substitute Alex Iwobi got in on the act, burying Cazorla's pass before drilling a low effort in off the post with nine minutes to play.
Chuba Akpom rounded off the scoring in the 89th minute to seal Arsenal's win, and put Wenger's squad into fine spirits ahead of Sunday's friendly with Manchester City.
Cazorla's spot-kick was well saved by Austbo, but Arsenal's control on proceedings eventually told 12 minutes before half-time, when Campbell turned in Mohamed Elneny's header following a corner.
Cazorla made no mistake when picking his spot in the second half, as he raced into space 20 yards out before rifling a left-footed shot into the goalkeeper's bottom-left corner to make it 2-0.
With the floodgates swinging open, Walcott made it three, smashing home from close range after being teed up by Campbell, and the Costa Rica forward doubled his own tally just six minutes later when he fired a shot in off the crossbar after Iwobi sent him free into the area.
The 20-year-old swept him his second and Arsenal's seventh as the Viking defence appeared to surrender completely, collecting Jeff Reine-Adelaide's pass before curling a low shot in off the far post from the left of the area.
