Celtic boss Ronny Deila believes James Forrest could prove the key to his side’s chances of Champions League progress this season.

The winger has been plagued by injuries in recent years, starting just 32 games in three years due to a combination of groin, knee, calf, hip and hamstring problems.

However, the Scottish international has returned to pre-season training looking much fitter and is set to play a leading role in the first leg of the Bhoys’ Champions League second qualifying round tie against Icelandic side Stjarnan.

Following a clerical error by Legia Warsaw, Celtic narrowly missed out on a place in the group stages for the third straight year as they went out to Slovenian outfit NK Maribor last season.

They are now due to begin another quest for a place at Europe’s top table on Wednesday against the Icelandic champions, with Forrest set for a starring role.

With his injury problems hopefully behind him, Deila admits the Scotland international has the potential to inspire his side and has backed the 24-year-old to impress.

“James can be very important,” he told the Scotsman. “He has something special on the ball. He can get past people and create chances. He looks strong.

“We have to be patient but we hope that he will be at a high level for these qualifying rounds. Last season he was at 40 per cent and now he is on 60-70 per cent. If we get him up to 100 per cent then everybody knows what his potential is.”

Although winning the Champions League is likely to be beyond Celtic this season, they remain the huge favourites at 1.03 to claim the Scottish Premiership for a fifth season in a row, with Aberdeen trailing behind at 21.00.