In the second half, Liverpool improved, as Jürgen Klopp moved Núñez to the left side.
Bayern Munich, with 13 points, have already been confirmed as the runaway winners of Group A.
With Saturday’s win, Arsenal displaced City from the top spot, garnering 30 points in 13 games this season.
The Gunners now have 17 points with wins and two draws in seven games, ranking third behind Liverpool with a goal difference.
Mike Arteta’s side returned to winning after a poor draw against Fulham last week.
The deal is the latest in Chelsea’s end of season players clear out as they seek to rebuild the team under new manager Mauricio Pochetinno.
Reece James finally managed to find the back of the net in the 25th minute, with the England international blasting the ball past Alisson Becker.
Chelsea made it three wins from three games across all competitions with the 3-1 away win.
Chelsea have progressed to the quarter-finals of the UEFA Champions League following a 2-0 win over Bundesliga side Borussia Dortmund.
Two goals from Kai Havertz and Mason Mount in the first half, gave The Blues a 2-0 victory, their first Premier League win since October.
