Dembele will be absent against the Andalusian club for the game at the Nou Camp, in the latest setback following his £136million move from Borussia Dortmund in August 2017.
The France international’s absence from training was reportedly due to his phone running out of battery, meaning it took an hour-and-a-half for him to notify the club of a stomach bug.
Dembele scored an 87th-minute winner for Barcelona in their last La Liga outing, a 3-2 win over Rayo Vallecano, but it has been an unhappy 15 months in Catalonia for the world's fourth most expensive player.
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Dembele has experienced a difficult time at Barcelona since his £136m move

Image credit: Getty Images

The 21-year-old was overlooked by manager Ernesto Valverde in the starting XI in last month's 5-1 win over Real Madrid despite the absence of Lionel Messi due to a broken arm.
Spanish outlet Marca reported this week that the club are unhappy at the way the player informed them of his illness, and Valverde said on Saturday: "The talent that Dembele has is difficult to find and we have to help him take advantage of it.
"We want the best from every player in our team. Dembele has incredible talent and we want to help him show it some day."
Messi joins Samuel Umtiti in returning to the squad as the Catalan club look to strengthen their position at the top of the table against 4th-placed Betis on Sunday.
After Barcelona officials finally got through to Dembele's phone following his missed training session on Thursday, club doctors were sent to him and they confirmed he had gastroenteritis.
Dembele was able to resume training on Friday, but he has been deemed not fit enough to play at the Nou Camp against Quique Setien's Betis side.
The Frenchman's debut season was plagued by a hamstring injury which mean he spent half of the campaign on the sidelines, while he has completed 90 minutes just once this term.
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