LONDON (AP) — Having spent nothing in the transfer window and with a depleted midfield, Arsenal rediscovered its Ox-Factor to reclaim top spot in the Premier League.

On his first league start since the opening day of an injury-curtailed season, Alex Oxlade-Chamberlain's first goals in more than a year gave Arsenal a 2-0 victory over Crystal Palace on Sunday.

"It took him a while to get back and I'm pleased he's now back to full fitness," Arsenal manager Arsene Wenger said. "He had shown today that he can be a very important player for us."

The 20-year-old midfielder broke through the resilient visitors two minutes into the second half, lifting the ball over goalkeeper Julian Speroni from close range.

And Oxlade-Chamberlain slotted in a second in the 73rd minute as he slotted seamlessly back into the injury-hit team.

"They made it hard for us in the first half," Oxlade-Chamberlain said. "But in the second half we knew if we kept the tempo up and kept wearing them down then we'd get more opportunities and we did."

A seventh 2-0 victory of the league season pushed Arsenal two points ahead of Manchester City, which hosts Chelsea on Monday.

The win sets up Arsenal for a challenging period ahead, with Liverpool (twice), Manchester United and Bayern Munich coming up in the next four fixtures.

And the victory should dispel concerns — for now — about Wenger not spending in the January transfer window.

But it was a first half as frustrating for fans as Arsenal's transfer inactivity. The only arrival — 31-year-old midfielder Kim Kallstrom on loan on Friday's deadline-day — has already been ruled out injured for up to six weeks before even getting the chance to pull on an Arsenal shirt.

By contrast, Palace was one of the most active clubs on deadline-day, although the four new outfield players weren't registered in time for Sunday's game.

Palace manager Tony Pulis is expecting the new arrivals to ensure the south London club, which is a point above the relegation zone, is a greater attacking threat in the coming months.

Arsenal completely dominated the first half on Sunday, although its route to goal congested by the disciplined visitors, who displayed the resilience at the heart of the team's revival under Tony Pulis since November.

Palace restricted Arsenal to just one shot in the opening half-hour, and that was from a defender. Goalkeeper Julian Speroni raced off his line in the seventh minute to meet Nacho Monreal, and block the shot with his right leg.

A diving save from Speroni in the 34th thwarted Laurent Koscielny's backward header from Mesut Ozil's free kick. From another of the Germany playmaker's free kicks, Per Mertesacker's header lacked power.

Arsenal ended the half with nothing to show for its 76 percent possession.

"It was very difficult to create space," Wenger said. "We needed to be patient, intelligent and use our opportunities that, most of the time, come in the second half."

Against Palace, it came immediately after the break, with the opener just reward for the slick build-up. Santi Cazorla weaved his way through the Palace defense and dinked the ball over for Oxlade-Chamberlain to score his first Arsenal goal since December 2012.

The lead was preserved by Wojciech Szczesny being alert to save Cameron Jerome's downward header and, after Podolski fired into sidenetting, Oxlade-Chamberlain found the target again.

Thomas Rosicky knocked the ball forward to Olivier Giroud, who backheeled it for Oxlade-Chamberlain to strike low into the net.

That ensured Arsenal extended its unbeaten run to 10 games in all competitions, and did not miss the suspended Mathieu Flamini and fellow midfielders Jack Wilshere and Aaron Ramsey, who are injured.