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Martin O'Neill's side had been cruising after netting three goals in 19 minutes, but Utrecht struck twice without reply to threaten a nervy conclusion, only for Auston Trusty's 66th-minute header to halt any chance of a comeback. 

Celtic made the ideal start in the sixth minute, when a short corner saw Kieran Tierney cross for Benjamin Nygren to finish past Vasilios Barkas from inside the six-yard box. 

The host doubled its lead four minutes later when Utrecht goalkeeper Barkas saw his pass intercepted by Nygren, whose cross was turned into his own net by Nick Viergever.

The Hoops pulled further clear soon afterwards, when they were awarded a penalty for Trusty's header striking the arm of Dani de Wit, with Arne Engels stepping up to ruthlessly dispatch from 12 yards. 

Utrecht had barely threatened in the first half, but they pulled a goal back a minute before the break, with De Wit taking a touch before curling the ball into the bottom-left corner. 

The visitor increased the anxiety around Celtic Park just after the hour as Adrian Blake rounded off a fine counter-attack with a curling effort past Kasper Schmeichel. 

But Celtic settled things down four minutes later through Trusty, who brilliantly glanced Engels' delivery into the top-right corner as they held on to seal a huge three points.