Olivier Giroud made the most of his first league start of the season by heading Arsenal to a 1-0 win over West Bromwich Albion on Monday and avoiding a third game without victory for Arsene Wenger's side.
Goalkeeper Ben Foster had repeatedly frustrated the hosts in a dominant second-half display but France international Giroud finally found a way through by nodding Mesut Ozil's arched cross beyond him in the 86th minute.
The striker's fourth league goal of the season returned Arsenal to winning ways following defeats at Everton and Manchester City, lifting them to third in the standings on 37 points, nine behind leaders Chelsea.
"Of course it was vital to win this game after the defeats, you don't want to play West Brom when you are under pressure. We were super favourites but you can have a big problem mentally when you don't win games," Wenger told reporters.
"We needed to stay patient and keep our pressure and we did that."
Albion coach Tony Pulis has had a prickly rivalry since Wenger since his Stoke days, the Frenchman once dubbing Pulis's side "a rugby team" for their physicality.
West Brom offered little in attack but still made life hard for Arsenal in the first half, limiting them to wayward shots from Granit Xhaka and Sanchez and a low strike from the Chilean which Foster tipped away.
Arsenal came alive after the break but kept coming up against the heroic Foster, who denied Alex Iwobi with a low dive and immediately rose to smother Sanchez, who rattled the post from the resulting corner.
It took the brute force of Giroud to get ahead of Albion defender Gareth McAuley and break the deadlock and Arsenal sought to further punish their visitors in the few remaining minutes.
"Gareth's got pinned by Giroud and he can't allow him to do that," Pulis said.
"He's untypical of what Arsene wants in many respects but he's got them the points today."
(Reporting by Richard Martin, editing by Ed Osmond)