At the same time in Manchester, relegation-threatened Nottingham Forest twice came from behind twice to rescue a 2-2 draw with City.
"It's not about this action or that action," City boss Pep Guardiola said.
"In the end we created a lot against a team that is really defensive ... Today we played in general good for 90 minutes."
This was a potentiality pivotal Wednesday night in the title race but Mikel Arteta's side were a long way from at their best, sloppy and slow in attack, careless with the ball and altogether too accommodating in letting the Seagulls play through them in midfield.
Most crucially of all, this was a third league win in a row and, on a night when City dropped points at home, one more fixture crossed out in Arsenal's race to the finish.
"I love my players. That's the highlight. I love my players and I love the way we compete," said Arteta.
"When you're in the position we are in, obviously (opposition fans) want to take that away from you. That's normal, that is sport."
A header from Rodri just after the hour put City back on course for victory after Morgan Gibbs-White cancelled out Antoine Semenyo's opener, but Elliot Anderson levelled for a second time at Etihad Stadium.
City do still have a game in hand on the Gunners, but Guardiola will rue another game in which his side lost control in the second half.
Elsewhere, Joao Pedro scored a hat-trick as Chelsea boosted their Champions League qualification hopes with a 4-1 win at Aston Villa.
Pedro's first Premier League treble saw Liam Rosenior's side move just three points behind a faltering Villa side in fourth.
Cole Palmer also scored for the Blues, who showed spirit to come from behind after Douglas Luiz's opener.
At St James' Park, Will Osula came off the bench to blast 10-man Newcastle United to a dramatic 2-1 victory over Manchester United.
The Dane struck in the 90th minute to end both Michael Carrick's eight-game unbeaten run as interim manager and the Magpies' return of three successive Premier League defeats in style.
Jacob Ramsey's dismissal sparked a frenzied conclusion to the first half during which Anthony Gordon put the hosts ahead from the penalty spot before Casemiro restored parity.
And a Crysencio Summerville goal for West Ham United sank Fulham 1-0 at Craven Cottage.
All three points moved the Hammers level with 17th-placed Forest, leaving them in the relegation zone only on goal difference.
