Sunderland manager Martin O’Neill believes striker Ji Dong-Won must improve physically in order to compete in the Premier League.
O’Neill was speaking after the Black Cats’ 3-2 victory over Dutch side FC Groningen, a comeback win in large part due to the efforts of young substitute Ryan Noble in a 13 minute cameo.
He told reporters: "Ryan Noble has gained valuable experience last season, and Wickham scored a goal today, showing his true ability.
"Ji Dong-Won is technically great but still has to become stronger physically. It's still quite early in the pre-season so it is hard to evaluate each players now."
O’Neill also praised the spirit of his side after they recovered from going 2-1 down to earn the victory in the closing minutes of the game.
He added: "Today we had an interesting match.
“We showed great spirit, turning the game around at the last minute.
“Moreover we had some young players with more experienced ones and they showed good balance."
Sunderland’s victory was thanks to goals from Connor Wickham, Frazier Campbell and a last-minute wonder strike from Noble, although defenders Wes Brown and Carlos Cuellar both had to be replaced in the first half due to injuries.
The Black Cats next face a trip away to Hartlepool United for their next pre-season friendly on July 27th as they prepare for the new Premier League season.