Manchester United have let their lead in the premiership slip to just three points after a shock two-one defeat at Portsmouth.A Matt Taylor strike and a Rio Ferdinand own-goal put Pompey in control, and John O'Shea's late effort proved merely a consolation for United.Meanwhile, Chelsea kept up the pressure on United closing their gap to three points after beating Tottenham Hotspur 1-0 at Stamford Bridge.Ricardo Carvalho's 52nd-minute strike for the Blues was enough to beat Spurs, just 39 hours after Martin Jol's men lost the first leg of their Uefa Cup quarter-final 1-0 in Seville.Mourinho was delighted to see his men continue their impressive unbeaten run against the north Londoners and take their tally of points up to 75 from their 32 games to date.The Portuguese said: "I am happy because for a long time we have not lost a single match. We have eight consecutive victories in the Premiership. We played well but Tottenham gave us a hard game."It is difficult to play in every competition at the same time. It is the same for Tottenham - they made changes and we made changes also. My players who were brought into the team, they did the job."Chelsea were scheduled to entertain Manchester United at Stamford Bridge next week but due to both sides' involvement in the FA Cup semi-finals that potential title-decider has had to be rearranged.Sir Alex Ferguson remains upbeat about his team. "We were coming off the back of a European tie and that's not easy at the best of times."We played for an hour with 10 men on Wednesday night and that caught up with us in the second half today."But we are still three points ahead and if I was given that at this stage at the start of the season I would have taken it," he said.© Independent Television News Limited 2007. All rights reserved.