Premier League - United claim win at Swansea
Javier Hernandez scored his fifth goal of the season and United's 1,800th under Alex Ferguson's management after a defensive error on 11 minutes. That was enough to settle United's first visit to Swansea since 1982 and see them reduce to eight-point advantage City had earned earlier in the day with their 3-1 win at home to Newcastle United.
Swansea began the day in eighth place, but Saturday's earlier results have seen them slip to 13th, below Norwich and Everton on goal difference.
The home side were roared on by a record crowd at the stadium they moved into in 2005 and began the match brightly, passing the ball freely and succinctly as they were not intimidated by the visit of the reigning champions.
However, they suffered a major setback when right-back Angel Rangel gave the ball away cheaply to Ryan Giggs inside the area, and the veteran Welsh midfielder marked his first ever league appearance against a team from his homeland by teeing up Hernandez, who beat goalkeeper Michal Vorm with a first-time finish.
That goal was the first scored at the Liberty Stadium by an opposition player since Swansea won promotion back up to the top flight - Bolton's goal in a 3-1 defeat last month was an own goal by Swans striker Danny Graham.
Swansea had the chance to make the champions pay for their below-par showing midway through the half. Some determined work in the build-up by Graham and Wayne Routledge allowed the latter to hit a low ball across the box. Scott Sinclair - last season's top scorer with 27 goals in all competitions - was perfectly placed to finish into the empty net, but the ball somehow slipped between his feet and the chance was gone in an instant.
Giggs struck a free-kick off target and Wayne Rooney had a half-hearted effort from range drift wide, but otherwise United could not create any clear chances other than the one gifted to them before half-time.
Nathan Dyer offered plenty of his usual pace and trickery on the break for Swansea, while Graham put in a tireless, but they too were unable to test David de Gea in the United goal in the first half.
Swansea boss Brendan Rodgers replaced Routledge with Joe Allen at half-time, and the substitute soon made an impact when he snuck a pass through for Sinclair, who drew a save from De Gea at his neat post.
With little more than 15 minutes left, Sinclair got past Jones at the byline and pulled a ball back for Graham. His shot was blocked, but the ball ricocheted back for Ashley Williams to shoot, but he too saw his effort stopped by his good friend Rio Ferdinand.
United were afforded what feels like the rare luxury of fielding their first-choice centre-backs, and both Ferdinand and Nemanja Vidic were dominant on the ground and in the air. As such, United were largely content to sit back and invite Swansea on to them in the hope of hitting them on the break.
The champions could have added a second in the closing stages - with Jones crashing a strike against the foot of the far post and Nani bending a shot wide with virtually the last kick of the game - but they left Wales with a third-straight 1-0 win.