Danny Welbeck scored twice as Arsenal edged out Southampton 3-2 in an incident-packed game to leave their opponents stuck in the Premier League's relegation zone.
Shane Long gave Southampton the lead but Pierre-Emerick Aubameyang and Welbeck put Arsenal in front and, though Charlie Austin equalised, Welbeck won it for the home side nine minutes from time.
Both sides ended the match with 10 men after Arsenal's Mohamed Elneny and Southampton's Jack Stephens were sent off late on.
Arsenal's sixth win in a row in all competitions put them two points behind fifth-placed Chelsea, who were playing West Ham United in the day's late match.
"Every game you win makes you stronger, it's important that you keep your run going," Arsenal manager Arsene Wenger said.
"We have gone through a difficult spell but, because the players are proud, we came back. Now we hope to keep this going."
Welbeck had not scored for 16 Premier League games but the England striker proved he has not lost his touch with a superb performance.
"I am very pleased for him because he is a guy who went through a very difficult time and has shown exceptional mental strength to come back," Wenger said.
Southampton remain third-bottom, three points from safety but with a game in hand over Crystal Palace in 17th.
Manager Mark Hughes was delighted with his side's endeavour but disappointed at the manner in which they conceded.
"We conceded poor goals, that's the story of our season," Hughes said.
"We showed real intent and purpose in the second half and got back on level terms but we needed to see the game out. That has been a problem all season.
"We have to take points from every game we play now. Performances like today will help our confidence. We have no fear, we will give it a go and you can see there is plenty of fight in the team."
In Sunday's other match substitute Javier Hernandez stole an equaliser to earn West Ham an unlikely point in a 1-1 draw with Chelsea at Stamford Bridge.
Chelsea had dominated the London derby for 73 minutes, leading for almost half that time after Cesar Azpilicueta poked home in following a short corner.
Their Spanish striker Alvaro Morata also had the ball in the net twice but was narrowly offside each time.
Manager Antonio Conte said the result summed up champions Chelsea's season.
"I think with this game we can see our season," he told the BBC.
"We can create a lot of chances but we cannot take them. Then we concede two shots and concede a goal.
"We have had good performances all season but you have to score. This is not the first time and we have to improve a lot. When you stay in this position in the table, it means that you have a problem."