Sir Alex Ferguson believes Manchester United "can take nothing for granted" as they prepare to face Liverpool in the FA Cup on Sunday, with their old rivals languishing four points above the Premier League's relegation zone and embroiled in a crisis that will almost certainly see Roy Hodgson removed from office.

United, in stark contrast, will go into the third-round tie at Old Trafford having moved into a position of strength at the top of the league, two points clear of second-placed Manchester City with two games in hand and nine points ahead of the champions, Chelsea.

Ferguson's men are unbeaten in the league and looking increasingly likely to establish themselves ahead of Liverpool as the most successful league team in English football, with a record 19th championship in their sights, but the manager was anxious not to say anything that could be construed as being overly confident when he was asked whether he had ever known the Merseyside club to be at such a low ebb coming into a United game.

"At the end of the day it's a cup tie and I'm taking it exactly that way," he said. "I'm taking nothing for granted. Liverpool will still be dangerous, absolutely. It's a cup tie and there are shocks in cup ties. There have been great reminders of that over the years, Hereford beating Newcastle, it's happened with Yeovil Town and York City, Bournemouth beating Manchester United. It's a tournament you can't take for granted."

It is perhaps a measure of how far Liverpool's stock has fallen that Ferguson should prepare for their visit by reciting some of the great FA Cup giant-killing acts of the past. United are already 19 points better off than Liverpool in the league although Ferguson, mindful of the history and rivalry between the two clubs, said he would not take chances with his team selection.

"The FA Cup is a tournament you can never be sure about. We made a mistake last year of picking a team that we thought would be good enough to beat Leeds and we got a reminder that the FA Cup has shocks in it [Leeds United won 1-0 at Old Trafford].

"It's the first time I'd lost a third-round tie since I came to the club and it didn't sit well with me. I was sick for a few days; I didn't enjoy it. Hopefully I will enjoy this better. I think I picked the wrong team last year and hopefully I don't pick the wrong team this time. We had a shock last year and we hope we don't get another."

Wayne Rooney, nursing an ankle injury, has "a reasonable chance of playing", according to Ferguson, while Rio Ferdinand is expected to return to defence after being given a night off when the team beat Stoke City on Tuesday. A late decision will be made on Edwin van der Sar, who has been suffering from a virus, with Tomasz Kuszczak on standby to replace the Dutchman and Anders Lindegaard, the newly signed Denmark international, coming into the squad.

Meanwhile Ferguson said Michael Owen still has a part to play at Old Trafford despite making only eight appearances this season, with three starts. "Now he is back fit, Michael will always be considered part of the squad and he will play in some big games," Ferguson said of a player whose contract expires in June. "I have not spoken to him about next season. There is no need to discuss that at the moment. He is a terrific player and a role model in the dressing room. He has never missed a session while he has been fit."