Manchester United emerged from a potentially problematic trip to Sunderland with a 1-0 win on Saturday to take another step towards a Premier League triumph that now seems inevitable.
An own goal from Titus Bramble extended United's unbeaten run in the league to 20 games and sent the 19-time English champions 18 points clear of Manchester City, who were due to tackle Newcastle United later on Saturday.
Sunderland, who have now gone seven games without a win, have not scored in more than seven hours of football and rarely threatened to find that elusive goal.
They are now serious candidates for relegation and the pressure is mounting on their manager, Martin O'Neill.
It was an excellent day for United manager Alex Ferguson, who engineered victory with a team that was far from full strength.
With the title virtually guaranteed, Ferguson had Monday's FA Cup quarter-final replay at Chelsea in his thoughts.
Wayne Rooney was rested and Tom Cleverley and Danny Welbeck made cameo appearances as substitutes after their mid-week action for England, although fellow internationals Chris Smalling and Michael Carrick were both involved again.
There was also no sign of Rio Ferdinand at the end of a week of controversy sparked by his withdrawal from the national squad and fuelled by abusive chants from England's fans.
There was some early encouragement for Sunderland, who had beaten United only once in 23 previous Premier League encounters.
Stephane Sessegnon twice suggested his pace might pose problems for United's defence and Craig Gardner had two shots blocked.
But there was a concern for O'Neill in the way Anderson was allowed space to advance into the area before his shot was repelled by goalkeeper Simon Mignolet in the 12th minute.
That warning was ignored, however, and further slack defending led to United's opening goal in the 27th minute.
There should have been little danger when van Persie collected the ball near the corner flag, but former United defender Phil Bardsley allowed him to advance to the edge of the area.
It was a fatal mistake, as van Persie was able to unleash a shot that clipped Bardsley before it took a decisive deflection off the knee of Bramble and flew into the net.
Sunderland were unable to craft a genuine first-half threat to the goal of David De Gea and only Mignolet prevented them going further behind before the interval as he twice saved from van Persie and also coped well with a shot from Ashley Young.
The second half was a non-event as United, anxious to conserve their energy before the trip to Stamford Bridge, went into cruise control.
Their chances dried up, although Sunderland, again lacking firepower in attack, were unable to capitalise on United's restrained approach.
Bardsley did manage a shot in the 59th minute, heralding Sunderland's best spell of the game, but United's stranglehold was not seriously jeopardised and they went close to a stoppage-time goal when Mignolet saved from van Persie.
In fact, their major concern was a collision on the hour between De Gea and Nemanja Vidic, with the Spaniard requiring lengthy treatment before he could continue.
There is no relief in sight for Sunderland, who now face awkward games against Chelsea, Everton and Newcastle United.
United, in contrast, have taken 50 points from their last 18 games and are on course to beat Chelsea's points record of 95.