Sir Alex Ferguson feels his Manchester United players need only take a look at what has happened to Barcelona in La Liga to see how quickly their fortunes could be transformed this season.
United head to Newcastle in a seemingly impregnable position at the Premier League summit. But it is only a matter of weeks since Barcelona were in a similar position. Now the gap to Real Madrid is down to four and Barca are suddenly wobbling.
"Barcelona have been playing Saturday-Wednesday-Saturday since January," said Ferguson. "They did have an 11-point lead, now it is four and for the first time this season they lost a game after being in front.
"It is a warning, and there are plenty of them, that if you take your foot off the pedal you can get a kick in the teeth."
Ferguson said United have to remain focused and, while he detects no sign among his younger players that a 'job done' feeling exists in the United dressing room, he is pretty sure his more experienced campaigners would stamp it out if it did emerge.
"They would have one attempt at being complacent and it would be the last," said Ferguson of his youth brigade. "We have plenty of bodies in the dressing room who would come down on them."
"I would be happy if we only won the Premier League from this point," he said. "It is a major trophy. "I would love to see us winning the Champions League again. That is my big desire. "But at this moment the Premier League has to be the best opportunity.
"If we keep our heads straight and focused we have a big chance." Not that Ferguson is willing to meekly surrender United's European crown to Jose Mourinho next week.
"We have done the hard bit in a way by going there and proving our worth," he said. "Now all we need to do is win our home game and we are through to the quarter final."