The Brazilian attacker, 32, collapsed with no other player around him late in Sevilla's 3-2 win in Warsaw on Wednesday.
Stretchered off the pitch, Matheus was later reported to have suffered a broken nose in an earlier clash of heads.
"It looks like everything is alright with him," Markevych said.
"He worked a lot on the pitch today so perhaps something went wrong, but I think everything is alright now."
The 32-year-old's sudden fall caused panic amongst players of both teams and evoked tragic memories for Sevilla, who lost Antonio Puerta to a fatal heart attack suffered duting a match in August 2007.
Matheus was treated for his injuries at hospital but Dnipro confirmed he was later discharged in full health.
"Matheus needed the help of doctors. The injury was so severe that the Brazilian was immediately sent to the hospital," read a statement on the club website.
"He was diagnosed with a fracture of the nasal bones and a head injury. A few hours later rejoined the football team at the hotel."
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