Yaya Toure scored his second Barclays Premier League goal of the season as Manchester City hit back from going a goal down to beat Swansea City.
Toure struck 17 minutes into the second half after Stevan Jovetic had cancelled out Wilfried Bony's early opener for the visitors.
Swansea boss Garry Monk threw on substitutes Bafetimbi Gomis and Jonjo Shelvey and they nearly snatched a late share of the spoils.
But Pellegrini's men held on to remain eight points behind leaders Chelsea, although they did move to within a point of second-placed Southampton who travel to Aston Villa on Monday.
Captain Vincent Kompany returned from a calf problem for the home team but a similar issue for Edin Dzeko contributed to Jovetic starting in attack.
Shelvey had to settle for a place on the Swansea bench following a one-match suspension, while Nathan Dyer returned to the starting XI - and the winger played a key role in the opening goal after eight minutes.
Bony raced on to a return chipped pass from Dyer to coolly slot past Joe Hart for his fifth BPL goal of the season.
The hosts offered little in return until Toure released Jesus Navas and the Spain winger played in an excellent low right wing cross to leave Jovetic with a simple finish.
Swansea goalkeeper Lukasz Fabianski brilliantly tipped a venomous Gael Clichy long-range strike on to the post after 39 minutes, and Pellegrini's men resumed on the front foot after the interval, before Hart was forced to save from Jefferson Montero after he had been involved in a slick exchange of passes with Bony.
It was end-to-end stuff in the second half and the hosts' Pablo Zabaleta streamed forward on the overlap to collect Navas's pass but blazed over left-footed having cut inside Ashley Williams.
Fabianksi was unsighted when Toure drilled goalwards in the 61st minute - he got down well to save but had no chance when the same player put Pellegrini's side ahead little more than a minute later.
Tom Carroll was careless in possession, allowing Samir Nasri to find Fernandinho in the Swansea box and his midfield partner charged on to a perfectly weighted backheel to prod home.
Man City then went for the kill and Jovetic curled over after Aguero's shot was blocked.
Navas became the latest attacker to be frustrated by Fabianski but late nerves afflicted the champions as Gomis spurned an 87th-minute one-on-one and Shelvey's deflected free-kick spun wide with Hart beaten.
Manchester City manager Manuel Pellegrini: "I am very happy because we won the game. We played very well and had a lot of chances to score the third goal and we defended well. It was a difficult start because they scored with their only chance in the first half.
"We are absolutely confident the way we play and sure we are going to win the game. If we scored the third goal we could play well and not so tight.
"We had the chances but didn't score. The best way to score goals is to play as a team. The second goal was beautiful play. We have to play seven games more before the end of December and we have to fight for all of them."
Swansea manager Garry Monk: "We are a little disappointed but they are a very good side and they had their chances. We had a couple of chances at the end we should have taken. I am just very happy with the journey we are on. We are competing in every game.
"We got a good goal and the players' mentality changed a little bit as we tried to protect it. A learning process for us, the players are fully committed. We pushed an exceptional team very, very close.
"Of course Manchester City will push for the title, I don't doubt that."
|20 Dec 2014||v Crystal Palace (H)|
|30 Nov 2014||v Southampton (A)|
|13 Dec 2014||v Leicester (A)|
|03 Dec 2014||v Sunderland (A)|
|06 Dec 2014||v Everton (H)|
|26 Dec 2014||v West Brom (A)|