Berbatov has United looking invincible

Arsène Wenger ought to have known that suggesting good luck had propelled Manchester United towards potential status as the new Premier League Invincibles might have its consequences. It was Alex McLeish, a manager with whom the Arsenal manager's relations have not always been cordial, who reaped them.

Wenger had suggested on Friday that the offensive side to United's game was not that of old, though the ease with which they rolled through the opposition yesterday suggested otherwise.

Dimitar Berbatov's third Old Trafford hat-trick of the season was complemented by the geometrical precision of Ryan Giggs and Wayne Rooney and aided by a Birmingham City defence which McLeish was not proud to call his own. Scott Dann's absence for the season's remainder is being felt, though his partner Roger Johnson will not have many worse afternoons than this and it was certainly no kind of homecoming for Ben Foster.

Not since Rooney in 2002-03 has a United player scored three hat-tricks in a season and Berbatov's imperious form at home – 15 of his 17 Premier League goals have come here – suggest he might push Alan Shearer's Premier League record of five set 15 years ago.

But it was Rooney, absent from the scoresheet again, whom Sir Alex Ferguson dwelled on. "We hope he will start scoring because he deserved one. He has worked his socks off," said the manager, who has still lost only five out of 66 games against former players who now manage.

Foster has reflected on his ultimately unhappy time at Old Trafford that the culture was "cut-throat" and "win at all costs," though the fragility which saw him lose his place in the United side were immediatelyapparent. The game was only 94 seconds old when Foster decided to stand rather than leap after John O'Shea propelled Giggs' corner into a looping arc to the back post, where Berbatov was waiting patiently to score. "Criminal" and "amateurish" was McLeish's description of his defence.

There was an ominous feel to proceedings from that moment which Foster seemed to sense and though United lost Michael Carrick early on – Alexander Hleb trod on his right foot as Steven Gerrard did here two weeks ago – they continued driving on. The inevitable second came just after the half hour when Johnson's poor clearance was seized upon by Anderson and navigated via Rooney to Berbatov who drove through poor Johnson's legs for the second. The third was imperious. Berbatov was on his knees when he intercepted a ball that he and Rooney exchanged twice before Rooney measured a low cross which evaded Johnson and Giggs lifted, first time, into the net seconds before the interval.

Rooney's finishing is still rusty – how he managed to head wide Nani's clipped cross just after the interval cross only he will know – though he was always the nexus, lacing anotherball through the legs of the hapless Johnson and into the left side of the area for Giggs to clip the cross for Berbatov's hat-trick.

It was a stroll, and though McLeish admitted he had an eye on this week's Carling Cup semi-final second leg, leaving Lee Bowyer and Cameron Jerome on the bench, David Bentley's minimal contribution bore out City acting chairman Peter Pannu's defence of owner Carson Yeung in yesterday's Birmingham Mail. Pannu said Yeung could not be accused of failing to spend because despite a £26.3m outlay "most of the purchaseshave not played much and have not substantially improved the team."

McLeish insisted it would be "madness" to sell Jerome, as it has been suggested he might, and that he needs another striker. "God loves a trier and I will go right to the death," he said of his the last transfer window week ahead. Defence was the problem, though. Nani took O'Shea's short pass to the edge of the area 15 minutes from and drove the fifth in left-footed. Only one word. Invincible.

Attendance: 75,326

Referee: Mike Jones

Man of the match: Berbatov

Berbatov's eight hat-tricks

15 Oct 2009: Georgia 2 Bulgaria 6

24 Aug 2000: CSKA Sofia 8 (Berbatov 5) Constructorul Chisinau 0

1 Apr 2006: Bayer Leverkusen 5 Kaiserslautern 1

21 May 2005: Bayer Leverkusen 5 Borussia Mönchengladbach 1

29 Dec 2007: Tottenham 6 (Berbatov 4) Reading 4

19 Sept 2010: Manchester Utd 3 Liverpool 2

27 Nov 2010: Manchester Utd 7 (Berbatov 5) Blackburn 1

22 Jan 2011: Manchester Utd 5 Birmingham 0