The Arsenal boss believes the Chilean has yet to fully click with his team-mates despite a promising showing, while he also singled out fellow new-boy Calum Chambers for praise
The Gunners were frustrated for much of Saturday's Premier League opener until Aaron Ramsey found a last-gasp winner to claim all three points against the managerless south Londoners.
Alexis, a €40 million arrival from Barcelona, assisted Laurent Koscielny's first-half equaliser, and Wenger, while pleased with his new signing's debut outing, has warned that the 25-year-old is still adjusting to life at the Emirates and has yet to reach full fitness.
"I am very happy with his attitude, because he kept fighting for 90 minutes – even though he is not completely ready physically," said the Frenchman.
"Tactically, he needs to improve his understanding with his partners. But he looked lively and dangerous until the end and I'm happy with his overall attitude and performance."
Another summer recruit who impressed was Calum Chambers, who once again deputised in the heart of the defence, and Wenger has been blown away by the Southampton academy product's rapid progress.
"I must say, honestly, I bought him as a right-back," continued the Arsenal boss, who would not be drawn on whether the teenager could permanently oust Per Mertesacker.
"But in my opinion [I thought] he could play centre-back. I tried it in pre-season and from game-to-game he becomes stronger. Today he had a remarkable performance."
While Wenger was pleased to pick up an opening-day victory, he conceded that Palace made life very difficult for his side and there are still areas to work on.
"The plan was to win the game but because of the physicality and the organisation level of Crystal Palace it was very difficult for us.
"We conceded the goal on the first corner they had and we still lack a bit of pace in the final third to change our build up into danger situations. But we kept going and in the end it was enough to win the game and win the three points.
"You could see from the first games of the season that nobody won at home. We are the only team that won at home, which shows you it is difficult for everybody on the first day of the season."