Football: Porterfield of quirky dreams: Phil Shaw on the weekend's Premier League action

'CHELSEA are the most unusual of clubs,' a club history from the Sixties explains. 'They have never done what every other club was doing at the same time as every other club was doing it.' Their endearing quirkiness endures, and Manchester United can be forgiven if they are unsure what to expect at Stamford Bridge in today's main attraction.

Ian Porterfield's side, now fourth and a point behind United, have almost risen without trace. They played poorly in their last home game, against Leeds, yet won with a late goal by Andy Townsend. 'Andy sets the standard for the whole team,' the manager said of his captain yesterday. 'He's the driving force.'

Victory over United and defeat for Aston Villa would send Chelsea into Christmas second in the Premier League five points behind Norwich, who face a derby with Ipswich on Monday. It is a peculiar prospect considering that Porterfield recently sacked his goalkeeper (Dave Beasant); lost his outstanding defender (Paul Elliott) for the season; and has seen his record buy (Robert Fleck) amass all of two goals.

Villa, who visit Manchester City, will have their pounds 3.9m strikers Dean Saunders and Dalian Atkinson reunited against a defence including the similarly expensive Keith Curle and Terry Phelan. Atkinson, back after injury, has 13 goals this season - and Villa have never lost a game in which he has scored.

George Graham, the Arsenal manager, was in Tommy Docherty's side when Chelsea last chased the title in 1964-65 (United, incidentally, finished top). The volatility of a division with no outstanding teams means it is premature to write off anyone, but Graham's men urgently need to beat Middlesbrough at home. Pondering a starting role for Ian Selley (18) and Mark Flatts (20) after four defeats, Graham said: 'I've never been afraid to throw the kids in. I'm not going to tolerate a situation like I inherited, with a lot of name players not performing.' The conduct of Ian Wright, who has not netted during Arsenal's barren run, will come under close scrutiny following his fracas with Spurs' David Howells.

Even more than Chelsea, whose mercurial season includes home flops against Sheffield United and Nottingham Forest, Liverpool and Leeds epitomise the leading clubs' fluctuating form. Witness Liverpool's last five League and Cup fixtures, in which they have won, drawn and lost against Crystal Palace, beaten Blackburn but succumbed to Everton.

Ironically, the main threat to them at Coventry is likely to come from a Liverpudlian, Mick Quinn, whom Bobby Gould signed from Newcastle this week after six goals in four loan outings. Eight years ago last weekend, in Gould's previous reign, Coventry defeated Liverpool 4-0 to go third. They hardly won again all season whereas Liverpool became champions. The Sky Blues have not taken full points since 14 September, so the match could again prove to be a watershed.

Tomorrow, resurgent Palace defend a four-game unbeaten matches against Leeds since Howard Wilkinson's side won promotion. The champions are desperate for a first away win - curiously, their rugby league neighbours also await that landmark - though ominously for them, Steve Coppell spoke yesterday of Palace reaching a 'turning point'.

Wright, Bright and Gabbiadini are long gone, but George Ndah (17), Grant Watts (19) and Bobby Bowry (21) look like the best young Eagles since Sansom, Hilaire and Nicholas emerged under the wing of a wily old bird called George Graham. Team of the Nineties, anyone?

MARCO VAN BASTEN, Milan's Dutch striker who is expected to be named European Footballer of the Year tomorrow night, is to have an operation on Monday to clean the cartilage of his right ankle. He will be out of the game for six to eight weeks. Van Basten had tests at a St Moritz clinic after missing Wednesday's World Cup qualifier in Turkey because of his injury. Milan can call on Jean-Pierre Papin, the current Footballer of the Year, to replace Van Basten, who won the honour in 1988 and 1989.