Chelsea floor Villa with Lampard's four

Frank Lampard passed the 150-goal milestone for Chelsea on Saturday with four goals in a 7-1 hammering of Aston Villa as Carlo Ancelotti's side roared back to the top of the English Premier League.

In one of the tightest title races for many years, Arsenal lost ground when they conceded a late equaliser at Birmingham City while Tottenham Hotspur strengthened their grip on fourth spot with a 2-0 home win against relegation-bound Portsmouth.

Lampard scored early for Chelsea from Florent Malouda's cross although there was no hint of the one-sided contest to come when Villa striker John Carew netted from close range on the half-hour to level the scores.

Lampard blasted home a penalty just before the break and the hosts then outclassed their opponents after the interval with the England midfielder scoring another from the spot before completing the rout with his fourth.

He is now the third-highest all-time goalscorer for Chelsea, overtaking Peter Osgood and Roy Bentley.

"When you take the work ethic the guy's got, it's no fluke, he works so hard day in day out. It's first class," Chelsea assistant manager Ray Wilkins told reporters.

"When you've consistently scored goals and played the way he has for so many seasons you have to say he is world class."

Rested top scorer Didier Drogba was hardly missed as in-form wide man Malouda scored twice and Salomon Kalou once to help Chelsea move on to 71 points, two more than champions Manchester United who were playing at Bolton Wanderers later on Saturday.

Significantly, Chelsea's goal difference has also been given a massive boost with 12 goals scored in a week, five of them coming at Portsmouth in midweek.

Third-placed Arsenal are a point behind United on 68 but had looked set to also move above them when Samir Nasri gave the visitors an 81st minute lead at Birmingham. But Kevin Phillips struck a stoppage time equaliser to deny Arsenal a vital win.

Goals from Peter Crouch and Niko Kranjcar against their old club eased fourth-placed Spurs to a 2-0 home win over Portsmouth that opened up a five-point gap over Manchester City who must wait until Monday to respond against Wigan Athletic.

Portsmouth's England goalkeeper David James hobbled off with a calf strain and defender Hermann Hreidarsson was carried off on a stretcher with a leg injury to increase the problems for the south-coast club marooned at the bottom of the table.

West Ham United's woes continued with a 1-0 home defeat by Stoke City that leaves them above the drop zone only on goal difference and adds to the pressure on manager Gianfranco Zola.

Hull City moved level with West Ham on 27 points thanks to a 2-0 home win against Fulham and they also have a game in hand.

Everton drew 0-0 with Wolverhampton Wanderers.