Guus Hiddink admits Chelsea might have spurned their best opportunity of overhauling Manchester United in the Premier League title race.
The west Londoners could have slashed United's advantage at the top of the table to a single point after Sir Alex Ferguson's side were surprisingly beaten 2-0 at Fulham on Saturday, their second defeat in as many matches.
But Chelsea failed to capitalise as they slumped to a 1-0 loss at rivals Tottenham, leaving their hopes of restoring the title to Stamford Bridge after a three-year absence in tatters.
Instead, it is Liverpool who now appear to have the best chance of making United sweat as the run-in gains pace over the coming weeks.
"We lost a huge opportunity, knowing that United were losing, it was a great chance to really change things," Hiddink said. "These are the typical days in a tough league. They are key moments. If Manchester United lose, we have to strike but we didn't do that.
"There's not just pressure on United but also ourselves and Liverpool. When you're chasing you have to win your games but to lose the goal as we did in the 10 minutes after half-time, with so many professionals and internationals, is bad for us."
Hiddink could barely contain his annoyance with his side, who were inexplicably lacklustre at White Hart Lane.
The Dutchman, who is in charge on an interim basis until the end of May, when he will return to manage the Russian national side permanently, was especially irritated by their sloppy start to the second half.
Chelsea, having been distinctly second best before the interval, compounded their woes with some flaky defending which allowed Aaron Lennon to exploit space on the right wing. The England international's cross was met first time by Luka Modric, whose excellent low shot found the bottom corner.
Falling behind knocked the stuffing out of the visitors and it was not until the last 15 minutes that Chelsea finally generated some meaningful attacking momentum. But Heurelho Gomes made fine saves from headers by Alex and John Terry and Spurs deservedly held on for a famous victory.
Hiddink will have plenty to ponder as he leaves England for the first time since his appointment at Stamford Bridge. He is due to travel first to Amsterdam, to visit his elderly father, and then on to Moscow where he will begin planning for the World Cup qualifiers against Azerbaijan and Liechtenstein.
But the former PSV Eindhoven manager refused to accept that Chelsea were distracted by his impending international commitments.
"We missed this opportunity due to our start in the second half," Hiddink complained. "We talked about that at half time. We knew they would come at us from the start and we emphasised that but it was very sloppy defence for their goal.
"Sometimes, there are circumstances where you can't always look for the best solution when the ball is in a dangerous part of the pitch: we have to just clear instead. We must learn from that."
Hiddink's dark mood was in stark contrast to that of Harry Redknapp, the Tottenham manager, whose side are suddenly eying a belated charge for seventh place, a finish which will guarantee Europa League football next season.
Redknapp could barely disguise his disdain for the UEFA Cup when he took control at White Hart Lane this season, and regularly complained that the extra fixtures placed too great a burden on his squad.
But he has attributed that attitude to Spurs' other commitments, rather than contempt for the competition itself.
"It wasn't that I disrespected the UEFA Cup - we were in a relegation battle and the League Cup final," he said. "I had to prioritise. If we had been in the top half we would have gone for it.
"We'll go for it again this season so let's push on and try and get seventh. We need to start looking upwards as a club - our recent form demands that because it's been terrific."