Arsenal came from behind to maintain their 100 per cent start to their Europa League campaign as two own goals helped them see off Molde.
The Gunners had already beaten Rapid Vienna and Dundalk in Group B and continued on their way to the knockout stages with a solid if unspectacular 4-1 victory at Emirates Stadium.
Martin Ellingsen’s long-range effort gave the reigning Eliteserien champions a shock lead against a slow-starting Arsenal side which showed nine changes from the weekend win at Manchester United.
Eddie Nketiah had an early chance after being picked out by Pepe, but his dinked effort was well saved by Andreas Linde.
There were very few opportunities to follow until Molde took a shock lead on 22 minutes, with a goal that was all of Arsenal’s own doing.
A Bernd Leno clearance was quickly worked back towards his goal by the visitors, with Ellingsen beating the German international too easily from all of 25 yards with a low finish.
It would soon prove to be an irrelevance, as Arsenal equalised moments later, Granit Xhaka leading a break forward, with Nketiah’s cross turned into his own goal by Haugen.
Arsenal were livelier after the restart and passed up a glorious chance to take the lead as Sead Kolasinac ballooned over an empty goal from three yards out after Linde had punched a cross into his path.
Another huge slice of luck saw Arsenal hit the front as Molde scored another own goal just after the hour mark – half-time substitute Sinyan only able to direct a Willock cross past Linde.
The game was wrapped up with a little over 20 minutes remaining as Pepe swept home at the end of a fine move started by man of the match Willock, with substitute Bukayo Saka crossing for the Ivory Coast winger to strike.
Nketiah had the ball in the net for a second time but again saw it ruled out, this time for an offside against Saka, whose shot hit the post before being turned home by the record England Under-21 goalscorer.
Molde almost reduced the arrears as substitute Leke James controlled the ball well before firing in a shot which deflected up off the boot of David Luiz and into the side-netting.
Instead, Arsenal would add a fourth goal of their own as Mohamed Elneny and Pepe combined to play in Willock, who finished with aplomb.