Walcott certainly played his part in that victory, which leaves Arsenal close to qualification for the knock-out stages.
"In the Champions League, you want to at least draw the away games, but we managed to sneak it in the end," he said.
"We were very solid at the back and we need to do that more often - dig deep and win games 1-0. It was nice to see that in Marseille.
"Now, hopefully, we can start climbing the Premier League."