Kris Commons' second-half header gave Celtic a 1-0 first-leg advantage over Swedish side Elfsborg in their Champions League third qualifier at Parkhead.
It was not a vintage performance from the Hoops who huffed and puffed for long spells against the organised and at times robust Swedish champions.
Both sides hit woodwork in an open and even first 45 minutes.
In the 20th minute Celtic wide-man James Forrest struck the crossbar with a volley which first bounced off the ground, following a whipped-in cross from Commons.
However, the visitors grew in confidence as the game went on and skipper Anders Svensson rattled the Celtic bar from 25 yards in the 31st minute, before heading over from a Stefan Ishizaki corner moments later.
Celtic had more of the play and possession in the second-half and got the breakthrough when Emilio Izaguirre planted a cross on to the head of the former Derby player who planted it past keeper Kevin Stuhr-Ellegaard.
Much of the attention was on Mo Bangura, who, as expected, took his place in the Elfsborg side against his parent club who had tried and failed to prevent the 24-year-old striker, on loan to the Swedes for one year, from playing in either of the ties.
Bangura was jeered each time he touched the ball but kept the Celtic defence occupied without causing material damage, although after getting stick from the home fans until he was substituted late in the game, he will be determined to do better next week.
After away victories at HJK Helsinki and Helsingborgs in last season's qualifiers, Celtic will travel to Sweden next week for the second-leg with added confidence although manager Neil Lennon will be looking for some improvement.
There was a decent crowd inside Celtic Park for the visit of the Swedish side.
Forward Derk Boerrigter, who signed for Celtic from Ajax on a four-year deal subject to international clearance on Tuesday, was not involved at all as the Hoops kept the same 11 which beat Cliftonville at home in the previous round, with Anthony Stokes leading the line.
Within seconds of the kick-off the Irishman latched on to a Georgios Samaras head-flick which breached the Elfsborg defence and volleyed across goal from a tight angle, the ball fizzing past the far post.
Strangely, Celtic looked anxious for the following few minutes allowing Elfsborg, with Bangura bustling and busy, to get a foothold in the game.
In the 15th minute Commons volleyed high over the bar from 12 yards after another good run by Samaras down the left-hand side.
After Forrest hit the bar with a volley from Commons' cross, Stokes had the ball in the net from a pass from the forward but the flag was already up for offside.
The Swedish side grew in confidence as the first-half flowed from end to end exemplified by Svensson's thunderbolt which crashed off the crossbar.
However, Hoops defender Efe Ambrose should have put Celtic ahead but headed a Commons' corner from six yards over the bar when he should have at least hit the target.
In first-half injury-time, Commons was fouled by Johan Larsson 20 yards from goal which led to Stuhr-Ellegaard having to make a good save from Anthony Stokes' free-kick at the expense of a corner which came to nothing.
The Hoops came out for the second-half somewhat energised.
A minute after the restart Samaras found himself with the ball at his feet eight yards out but hit it straight at Stuhr-Ellegaard.
There was an unsuccessful Celtic appeal for a penalty in the 65th minute when Samaras's shot was deflected past by Elfsborg defender Daniel Mobaek, just before Joe Ledley replaced Beram Kayal.
Bangura further irked the home fans when he went to ground after a harmless-looking tussle with Wilson on the touchline with Portuguese referee Manuel Se Douda unimpressed.
It was proving to be hard work for Celtic, as Elfsborg dropped deeper looking to hold out for the draw.
However, Commons' goal gave Celtic the lead they desired and as they pushed hard for the second goal, a Samaras header was cleared off the line by Andreas Klarstrem.