Jo has scored two goals in 24 appearances this season
Everton have suspended on-loan striker Jo for a breach of discipline after the Brazilian returned to South America without permission over Christmas.
Jo, 22, is in his second loan spell with Everton from Manchester City.
"We like Jo but there has to be discipline at football clubs," said Everton boss David Moyes.
"He left over a busy period and left us short of players. We've suspended him from the club. It might change but at the moment that's the situation."
The 6ft 3in forward, whose full name is Joao Alves de Assis Silva, scored 44 goals in 77 games for CSKA Moscow before joining City in July 2008.
He signed a four-year deal for a fee thought to be in the region of £18m but struggled to adjust to the Premier League and, following a return only three goals in 18 games, joined Everton on loan for the second half of last season.
After returning to Eastlands at the end of the campaign, Jo rejoined the Toffees in July but has been largely used as a substitute, scoring two goals in 24 appearances.
South American players often return home for the Christmas break and late returns have been a recurring problem for European clubs.
Schalke 04 defender Rafinha did not turn up for training on Wednesday and failed to justify his absence, according to coach Felix Magath.
Peru forward Jefferson Farfan and Brazilian defender Bordon were also absent but they had obtained permission for a late return after the Christmas break.
Rafinha defied Schalke last year when he joined Brazil's Olympic Games squad after the club initially refused to release him to play in Beijing.
The Court of Arbitration for Sport (CAS) later ruled in Schalke's favour but the club then agreed to allow Rafinha to stay in China.
Meanwhile Moyes has told sacked Preston manager Alan Irvine, who was the Everton manager's former assistant before he moved to Deepdale, that he is welcome to come in and work at the Merseyside club's Finch Farm training ground.
"I have said to him he is welcome to come in," said Moyes. "He is a student of the game and won't sit at home.
"Alan has done such a good job he will undoubtedly work again. It would not surprise me if he gets one of the big jobs going around at the moment."
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