Wenger started both players for the 2-1 win.
Wenger told arsenal.com: "I feel both are short [of fitness] a bit, they lack competition and their second half was much better than their first half. They were a bit surprised by the pace and the commitment of the Premier League [but] they will adapt to that. As well, they were a bit on their nerves in the first half. In the second it was much better."
On Lucas, he continued: "He has had one game in La Liga, and then he didn't play many more because they knew he would go. Mustafi has only played one half since the start of the season with Valencia, so they are missing games."