David Moyes has played down Jo's injury and is confident the Brazilian will be fit for the start of the season.
The Everton striker limped out of Tuesday night's friendly defeat at Blackpool after injuring his ankle.
It proved to be a mixed evening for the Brazilian, on a season-long loan from Manchester City, as he scored an equaliser before hobbling off.
Jo left Bloomfield Road on crutches but Moyes, however, has played down the seriousness of the injury.
"I think he's just rolled his ankle. I don't think it's too bad," he said.
"Hopefully he'll be all right, and it wasn't too serious."
Fellow striker Louis Saha, midfielder Steven Pienaar and defender Joleon Lescott - a target for Manchester City - all missed the friendly with injuries which will be assessed later in the week.
Lescott and Pienaar could be in line for a return against Malaga at Goodison Park on Friday.
"In Salt Lake City Joleon jarred his hip just after half-time. He's okay, but it's a bit sore," head physio Mick Rathbone told evertonTV.
"He's making progress, and we hope to have him back sooner rather than later.
"Steven got a minor thigh strain (against River Plate in the first game of their US tour).
"He's been running okay and again we're looking at the Malaga game, hopefully, for him."