Jon Brodkin on how Jose Mourinho has moved quickly to halt the 'decline'

It may sound unusual for a manager to tell his team to buck up their ideas when they lead their domestic league by nine points, but Jose Mourinho has done precisely that before Chelsea's game at Manchester United tomorrow. Far from showing he has lost touch with reality after his attack on Arsene Wenger, it underlines the manager's concern at his squad's form and attitude. Without a change he fears the chasers will soon be able to spot Chelsea without a telescope.

If the idea of the champions being caught still seems far-fetched, the certainties have been stripped away sufficiently for Mourinho to act. A League Cup exit to Charlton could be brushed aside and a two-goal lead surrendered against Blackburn did not matter in the end, but Mourinho's fears were confirmed by defeat at Real Betis. The Spanish club had been beaten 4-0 at Chelsea two weeks earlier and lost their previous four matches.

When the 42-year-old suggests the absence of an obvious challenge in the Premiership is to blame, he is not being arrogant. He feels the lack of pressure on Chelsea has caused a drop in concentration, adrenalin and performances. At a meeting on Thursday he warned the team to regain their old levels or risk seeing their advantage at the top of the league whittled away. No one, he emphasised, should view the Premiership as too easy.

"It's stupid if we think that," Mourinho said, "but the reality is that last season we had much more pressure and our reaction was much more positive. (Early in) the season (we were) five points behind Arsenal and knew we could not make any more mistakes. Even when we went top of the league it was always only one, two, three, four points. We were winning and they were winning.

"At the beginning of this season there was not this kind of pressure and it looked easy for us. But if we make mistakes and mistakes and mistakes and lose one, two, three matches, in one or months instead of being 10 points ahead we can be only one point ahead. Are we waiting for that to perform again? That's the discussion we had. Are we waiting for that pressure to perform again? So we must perform even if the distance is a good distance."

As Manchester United and Newcastle will testify, seasons ending in "6" have not been kind to top-flight teams with significant leads. When Ron Atkinson was manager at Old Trafford his side won the first 10 matches of the 1985/86 season to claim a nine-point advantage over Liverpool, the eventual champions, but finished fourth, 12 points off the top. Atkinson says injuries tripped up his challenge and it is hard to imagine Chelsea suffering the same fate.

Newcastle famously blew a 12-point lead over Manchester United in 1995/96 and were top of the table until the end of February. But whereas their manager Kevin Keegan seemed vulnerable to mind games and his team had no experience of winning the championship, Mourinho and his players are a different breed.

The sight of Chelsea going to Old Trafford heading the Premiership and unbeaten in 40 league matches must leave their challengers hoping for a repeat of Arsenal's experience at the same stadium last season. Wenger's players arrived with the swagger of a team who had not lost for 49 league games but a 2-0 defeat sent them into a spiral of uncertainty and poor results from which they could not recover.

Greatness can be fragile but Mourinho does not fear an identical fate for his players if they lose.

"The difference is that we have a big lead so we can keep cool," he explained. "When Arsenal lost there we went within one or two points of them. After that the pressure was right on them. Lose one more game and you lose first place. Our situation is a good one. Independent of the result we are ready to carry on."

He is, in fact, delighted to face United. Alex Ferguson's side may be in a slump and 13 points behind Chelsea with a game in hand but Mourinho knows his team will be switched on for such a match. He sensed they took victory for granted at Betis but is sure the desire will return.

"There can be a difference of 30 points when it's Chelsea against Manchester United or Arsenal and it won't make a difference," he said. "They are the most difficult matches to play but the easiest matches to prepare for because I don't have to motivate the players."

Mourinho argues Chelsea's players need to feel under pressure because they are "used to playing for big things". He noted how the side's defending had slipped of late as they stopped being "afraid" of conceding goals because of the frequency with which they recovered to win (against Aston Villa, Bolton and Blackburn) or draw (at Everton) before going to Betis. "You need to be more worried in your defensive actions," he said. He hopes normal service will resume now.

"Last season we were not scoring many goals so we knew if we conceded we were in trouble," Mourinho said. "This season that's not the case . . . It looks like it doesn't matter if the opponent scores before us, if at half-time we are not winning."

Chelsea are unlikely to underestimate United. Mourinho had expected the gap between the clubs to be far smaller but rejects the idea the pressure is off. "I think we need pressure so I prefer to say the pressure is on us because we lost," he said. "I thought it would be a very, very short distance but the distance is quite big. But in football there are many examples of things turning around."