Spartak striker Welliton may miss Chelsea clash
"Welliton has a minor muscle tear of his left thigh. It'll take him two to three weeks to recover," Spartak said on their website.
The Brazilian, who suffered the injury in the second half of Spartak's 3-0 victory over Slovakia's Zilina on Tuesday, could miss his team's next match in the Champions League - the top-of-the-table Group F clash against Chelsea on October 19.
Welliton has led the Russian Premier League in scoring for the second consecutive season with 16 goals in 21 matches after notching 21 last year.