Martin O'Neill gave a blunt and brutal assessment of Celtic's issues after their Europa League thrashing by Stuttgart, slamming a fan protest, explaining how a Premier League switch could boost their European prospects and defending Kasper Schmeichel.

O'Neill's side are all but out of their knockout play-off with Stuttgart after a 4-1 humbling in the first leg at Celtic Park.

The game was halted inside the opening seconds when fans threw balls onto the pitch to highlight their frustration with the club's board, while goalkeeper Schmeichel was later booed after making errors for Stuttgart goals.

Speaking afterwards to TNT Sports, O'Neill described his team as "masters of our downfall" but also pointed to problems beyond the pitch, including Celtic's limitations in the transfer market, saying: "Eventually, if the SPL [Scottish Premiership] belonged to the Premier League, I don't think we'd have a problem."

On the prospect of Celtic pulling off a turnaround in the second leg, he conceded: "At some stage, Celtic will become a top-quality European team. That's in the future. But at this minute, our battles are elsewhere."

Celtic's crucial run of games

• Hibernian (H), Sunday, February 22 - Scottish Premiership
• Stuttgart...