Chasing a fifth successive victory at the start of its Premier League title defense, Manchester United hosts Chelsea on Sunday knowing it should not get carried away with its early success.
After all, Chelsea opened its defense last season with five wins before a slump saw the London club surrender the trophy to United and cost manager Carlo Ancelotti his job.
United has appeared to be almost unstoppable this season, with its irrepressible attacking unit scoring 18 goals in the four wins so far.
The champions are above neighbor Manchester City on goal difference, while Chelsea - now managed by Andre Villas-Boas - is two points back in third.
City, which has scored 15 goals in its four victories, visits Fulham on Sunday.