Mikel Merino led Arsenal to a 1-0 win against Chelsea in the Premier League on Sunday.
Merino's first-half header settled the London derby at the Emirates Stadium and saw second-placed Arsenal move within 12 points of leader Liverpool.
In another all-London clash, Fulham beat Tottenham 2-0.
Arsenal's title hopes have faded in recent weeks, but it closed the gap on Liverpool, which was playing Newcastle in the English League Cup final later in the day.
Merino rose in the 20th minute to flick Martin Odegaard's near post corner beyond Chelsea goalkeeper Robert Sanchez. It was enough to secure a first league win for Mikel Arteta's team since February 15.
Defeat for fourth-placed Chelsea means it missed the chance to extend its one-point lead over Manchester City in fifth and boost its chance of qualifying for the Champions League next season.
Arsenal, on 58 points, is 10 clear of four time defending champion City.
Spurs blow
Another setback for Tottenham is likely to increase the pressure on coach Ange Postecoglou heading into the international break.
Spurs, in 14th, have only won one of their last five in all competitions and this was a 15th league defeat of the season.
Rodrigo Muniz gave Fulham the lead in the 78th at Craven Cottage and Ryan Sessegnon doubled the home team's lead 10 minutes later.
Fulham is eighth and four points behind Chelsea in the race for a Champions League place.
