Sir Alex Ferguson admits he has 'no idea' how Chelsea will line up against leaders Manchester United on Sunday.
The Blues travel to Old Trafford searching for the win that would swing the Premier League title race back in their favour, as three points separate the pair with an identical goal difference.
Chelsea boss Carlo Ancelotti has chopped and changed his side repeatedly since the turn of the year, with the January arrival of Fernando Torres providing him with a constant selection headache.
Ferguson watched Chelsea's 2-1 win over Tottenham last Saturday, but he concedes the performance brought little to light as Ancelotti's line-up remains a guessing game.
"I have no idea what to expect from Chelsea," he said. "I was at their game last week and couldn't get anything from that.
"Drogba played the whole game so you would expect him definitely to play. But he started off wide right, then Torres went there.
"Whether they start with both of them on Sunday is difficult to say. But no matter what they do, we have the players to handle it."
Chelsea enjoyed a 2-1 win over United in the Premier League in March, a game which revitalised their season and ignited a late push to retain their title.
Ferguson was highly critical of referee Martin Atkinson's performance that day, earning a five-match touchline ban for his post-match comments.
"That result was the change for them," said the Scot. "We all know the circumstances of that game and I don't need to get into that.
"But the outcome gave them a lift. They were out of the game and they had won it."
Ferguson is aggrieved to have allowed the Blues back into contention, having recently lost away to Liverpool and Arsenal, but he believes little can be taken for granted in the Premier League.
"Us losing to Arsenal has opened the door for them," Ferguson added. "But we always said it is a very difficult league.
"The Premier League is hard to win. We know because we have been involved in the championship races for 19 years."
What will be the outcome in the match Man Utd vs Chelsea?