Maresca could be forced to turn to the untested members of his squad

ENZO MARESCA will be anxiously checking his phone on Wednesday morning as his South American stars compete in their countries’ final World Cup qualifiers.

Brazil internationals Joao Pedro, Estevao, and Andrey Santos will travel back to London from Bolivia after a match at the highest international stadium on the planet.

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Estevao is one of a number of Chelsea players taking part in World Cup qualifiers this weekCredit: Getty

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Cole Palmer missed England duty with injuryCredit: Getty
La Paz’s Estadio Municipal de El Alto sits at an energy-sapping altitude of 4,150m — or 13,615 feet — above sea level where tourists often need days to adapt to the lack of oxygen.

Playing football there was banned by Fifa in 2007 — until a campaign backed by Diego Maradona saw that decision reversed.

Neymar described his experience as “inhuman” after a World Cup qualifier in 2007 at a different stadium in the city — 560m lower than El Alto — where Brazil’s players wore oxygen masks in the changing room after struggling to a 0-0 draw.

So Maresca can expect Pedro, Estevao and Santos to return to the club’s Cobham base later this week out of breath and exhausted following a 14-hour flight.

Midfield dynamo Moises Caicedo will also be returning from Ecuador on a long flight ahead of the Blues’ Prem derby clash at Brentford on Saturday evening.

Those marathon journeys will give Maresca a massive selection headache ahead of the potential banana skin fixture.

All eyes will be on Thursday’s training session to see who makes it and who will return to action on Friday before Saturday’s 8pm game.

Either Pedro, Caicedo or Estevao have been involved in every one of Chelsea’s seven goals this season — showing how heavily they have leant on their South American stars.

The Blues have seven players from the continent in their first-team squad — the highest number from any club in the league.

Maresca, though, can at least rely on his three Argentine players.

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Chelsea’s new boys Facundo Buonanotte and Alejandro Garnacho were not selected by Lionel Scaloni, while Enzo Fernandez enjoyed a Greek getaway with his family, absent from his national team due to suspension.

After injuries to Palmer, Liam Delap, and Levi Colwill, the Blues’ medical room has become even busier – as Dario Essugo picked up a knock while away with Portugal.

The 20-year-old, who signed from Sporting for £18.5million this summer, sustained a thigh injury on international duty and is now expected to miss up to three weeks.

Essugo was bought in primarily as cover for the seemingly indestructible Caicedo, but the Ecuadorian midfielder has also been struggling this season according to Enzo Maresca.

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Brazil’s squad needed to take oxygen tanks when facing Bolivia in 2017Credit: Instagram @cbf_futebol

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The players had to breathe with the tanks in the dressing roomCredit: Instagrm @neymarjr
So much so, that Caicedo was missing from Ecuador’s 0-0 draw against Paraguay due to ‘physical discomfort’ – though he is expected to feature against Argentina on Tuesday night.

That leaves Chelsea, who have a midfield worth more than £300m, facing a problem with Romeo Lavia also out and not ready to return.

If Caicedo is forced to miss any upcoming games for Chelsea, they may have a midfield depth of Santos, Fernandez and Reece James.

Maresca’s side, however, will be hoping to be boosted by the return of Cole Palmer, who teased he will be ‘back soon’ in his latest Instagram post.

It remains unclear exactly how soon that might be but the Chelsea boss will be hoping, if he does miss the game against Brentford, he will be back in time for a huge Champions League tie away at Bayern Munich four days later.