The Chilean scored, won a penalty and provided an assist as Arsene Wenger's men continued Watford's poor start to the new campaign. Arsenal were 3-0 upand in cruise control by half time.
The show opened with a lengthy video package summing up Seth Rollins and Dean Ambrose's story to date, including Rollins turning down a reconciliatory fistbump from Ambrose last week.
With the Gunners trailing 2-0 and a man down following Dani Ceballos' sending off, Pepe stepped upand fired home a precious away goal from the spot after Bukayo Saka had been tripped in the box.
Gylfi Sigurdsson won a penalty in the 59th minute after being brought down by Thibaut Courtois inside the box, before then getting back up on his feet to slot the ball past the Belgian from the spot.