Robin van Persie could be the difference, scoring 10 goals in 10 top-flight matches and taking his tally to 20 goals this season. The Dutchman gave United the lead and turned provider for the next but could have easily netted more.
United's 55 points in 22 games is the highest tally of a Premier League season. Their closest rivals Manchester City overcame a deficit of eight points last season and are still in the hunt after beating Arsenal 2-0 at the Emirates.
United secured the double over Liverpool after five seasons but the 2-1 win cost them as Ashley Young and Nemanja Vidic were withdrawn due to injuries. The last time Vidic joined Rio Ferdinand at the back was in September but Sir Alex Ferguson has reinforcements in Phil Jones, Chris Smalling and Jonny Evans who is currently injured.
The Red Devils attacking options can scare any defence in the league, scoring more than any other team with 56 goals. But they have conceded 29 goals so far, 10 more than Manchester City and Chelsea, which underlines their problems at the back.
Moreover, United have gone down first on 16 ocassions, relying on forwards to do the job under pressure. But the league leaders are finding their feet in midfield.
Tom Cleverley is showing promising signs of controlling play along with Michael Carrick in the middle. Cleverley, 23, tipped to be the next Paul Scholes, has also been scoring lately. The England international now has four goals this season. Another rising star for United is Shinji Kagawa who was all over the pitch against Liverpool.
Welbeck was named Man-of-the-Match for his performance but United still have much more force in attack. Javier Hernandez has bagged a few goals while striker Wayne Rooney has linked well with Van Persie.
With the furture of veterans Scholes and Ryan Giggs uncertain, United have to rely on Cleverley and Carrick while Darren Fletcher is another midfielder they can bank on. Rooney has switched to a midfield role along side Kagawa while Ferguson is not short of wingers. Young, Antonio Valencia and Nani can play on either flanks.
Ferguson has countless attacking options, reliable midfielders and a strong defence line.
United have got the better of City, Chelsea, Arsenal and now Liverpool, but now face fourth place Tottenham who beat them 3-2 back in September. The 19-time champions cannot think of dropping points from here on as City close in but the record 20th league title is up for grabs.