Chelsea's season has to "start now" according to Frank Lampard, whose side wasted chances and endured VAR frustration as they lost 2-0 at home to Manchester United.
The Blues, who face Tottenham next, have now won just one of their past six Premier League matches after Monday's defeat at Stamford Bridge, with their place in the top four under serious threat.
Manchester City's ban from the Champions League – should it be upheld – will mean fifth place could be enough for a Premier League side to qualify for Europe's top-tier competition for next season.
However, just seven points separate Chelsea and Arsenal in 10th in what has become a congested race for Europe.
Lampard felt aggrieved that VAR was not on Chelsea's side against United, with Harry Maguire escaping a possible red card for a clash with Michy Batshuayi and the Blues seeing two goals disallowed in the second half, but he again pointed to his side's profligacy in front of goal as a factor in their defeat.
"It's tough to take on lots of levels, some footballing, some others," Lampard, who was without leading scorer Tammy Abraham due to injury, told Sky Sports.
"It's frustrating, but that's life. I'm not upset with the work ethic or input. Their heads are down in there and I have to correct that. It's not a 2-0 game but the reality of football is that it is a 2-0 game because of moments.
"We have a feeling of Groundhog Day, whatever you want to call it. There are footballing things, which get clearer every week.
"There's always work to do every day. At the minute, we're fourth and the season starts here. There are things I can criticise; I'm not soft. If we're not going to have productivity to finish, it's very difficult to win games."
Anthony Martial gave United a half-time lead but Kurt Zouma thought he had restored parity early in the second half, only for the goal to be ruled out for a foul by Cesar Azpilicueta, who was deemed to have pushed Brandon Williams.
Olivier Giroud's header was then disallowed for offside after Maguire had made it 2-0 from a Bruno Fernandes corner.
"Maguire should get a red card and then he scores the second goal, and the game changes off that," Lampard, who also confirmed N'Golo Kante had suffered an adductor injury, said in a news conference.
"That's a major part of what VAR was for. The referee can't see all the angles and if you're not going to use the monitor, I don't understand it.
"The Zouma goal should have stood. Azpilicueta gets shoved in the first place. It's certainly not clear and obvious. It's just a wrong decision, isn't it, which is harder to take with the presence of VAR than it would have been before.
"Love it or hate it, if something happens and they don't make the right decision, it's very confusing to say the least. Everyone I've spoken to has said the same thing."