Chelsea manager Enzo Maresca says it is "impossible" to organise normal training sessions amid a "code red" severe heat warning in Philadelphia at the Club World Cup.

The Blues players trained at Subaru Park, the home of local Major League Soccer (MLS) side Philadelphia Union, in 37C.

The 45% humidity means it feels more like 45C, according to accuweather.com, and temperatures on Monday were predicted to top 100 degrees Fahrenheit (37.8C) for the first time in 13 years.

"This morning's session has been very, very, very short," said Maresca, adding that "otherwise you don't save energy for the game".

"It's been just about tomorrow's game, planning for tomorrow, and that's it. No more than that," the Italian added.

"As you can see, it's not easy in these conditions with these temperatures. We are going to try to do our best."

The local public authority has warned people in Philadelphia to avoid "work in high-heat environments" and "strenuous physical activity".

However, some matches at Fifa's newly expanded tournament have kicked off in the middle of the afternoon, with temperatures at their highest.

"It's difficult to work with these temperatures but we are here and we trying to do our best and we will try to win tomorrow," said Maresca.

Similar problems have been faced by other clubs, raising concerns about the United States co-hosting the World Cup at this time next year.

Borussia Dortmund manager Niko Kovac said he was "sweating like I've just come out of a sauna" after his side beat Mamelodi Sundowns in 32C heat in Cincinnati on Saturday.

After Atletico Madrid's 4-0 defeat by Paris St-Germain in 32C in Pasadena, midfielder Marcos Llorente said it was "terribly hot" and added "my toes were sore, my nails were hurting - it's incredible".

Chelsea are under pressure for their final Group D match against Tunisia's ES Tunis after losing 3-1 to Brazilian club Flamengo last time round.

The Blues need to avoid defeat to qualify as runners-up, which would secure a last-16 tie against Bayern Munich, Benfica or Boca Juniors.

Captain Reece James is a doubt because he is "ill" and Nicolas Jackson is suspended after his red card last week and was left out of the open training session on Monday.

How are Chelsea fighting the heat?

Chelsea's players had what was described as a "very short" training session at Subaru Park as medical staff watched on.

There were crates of iced water bottles around the pitch and drinks offered at every opportunity in between drills.

Huge fans were placed on the sides of the pitch, blowing water spray at the players, and they trained in the only partially shaded area of the open stadium in Chester, Pennsylvania, just outside Philadelphia.

When asked about the conditions, defender Marc Cucurella said: "It takes some getting used to, and it's true we played a lot of games last season, but we know we have a job to do here, and we want to go far in the tournament."