Everton midfielder Bryan Oviedo will undergo a scan on Tuesday to learn the extent of a hamstring injury.
The Costa Rica international impressed when Everton beat Norwich on penalties to progress to the quarter-finals of the League Cup last week.
Oviedo did enough to retain his spot for the 6-2 win over Sunderland on Sunday, but lasted just 24 minutes of the Premier League encounter before pulling up injured.
Everton subsequently posted on Twitter: "Roberto Martinez confirms Bryan Oviedo will have a scan on his hamstring today [Tuesday]."
It marks the continuation of a hard luck story for Oviedo, who has been blighted by injury over the past two years.
Oviedo suffered a double leg break in an FA Cup encounter against Stevenage in January 2014, which ruled him out of the World Cup that year.
After returning to fitness, he suffered a hamstring injury in February 2015 and two months later sustained a broken metatarsal.
