Celtic needed a late strike from Kris Commons to secure a 1-0 home win over Elfsborg in the first leg of their Champions League third qualifying round match on Wednesday.
Anthony Stokes missed an early chance for the Hoops before James Forrest saw his effort hit the crossbar.
However, Elfsborg, who named on-loan Celtic striker Mohamed Bangura in their starting line-up, had opportunities of their own and Hoops keeper Fraser Forster did well to stop a fierce strike from veteran Anders Svensson.
Things turned ugly in a fiercely-contested second half in Glasgow with a spate of bookings for both sides.
Celtic had a penalty appeal turned down and a Scott Brown strike blocked before Commons headed Celtic into the lead in the 76th minute.
It means the Scottish champions will only take a slender advantage to the Boras Arena, where Elfsborg haven't been beaten since September 2011.
Celtic manager Neil Lennon was delighted with his side's performance and result.
"It was our first real competitive game and there was obviously some rust there," he said.
"We had to be patient and Elfsborg made it difficult for us to break them down but the crucial thing is a clean sheet as well.
"The tie is probably still in the balance but we are confident we can go there and get a result as well."
His Elfsborg counterpart, Jorgen Lennartsson, was disappointed with their second half showing.
"It was a very good first half and we played exactly in the way that we hoped tactically," he said.
"In the second half we were a little bit too deep defensively and we didn't have enough possession but we think the tie is still alive and we are a very good side at home."
Celtic had named an unchanged line-up to the one that saw off Cliftonville last week as they looked to make home advantage count.
They nearly got off to the perfect start when Samaras nodded on a ball for Stokes who hooked his shot wide after just 15 seconds.
Before the match the headlines had all been about Bangura and the on-loan striker's every touch was accompanied by a chorus of jeers from the home fans.
The Sierra Leone forward had failed to score for Celtic in 16 appearances but soon tested Forster with a low drive from 25 yards that the keeper got down well to stop.
Celtic came close to breaking the deadlock after 20 minutes when Commons' cross from the left was met by James Forrest at the far post and his first-time effort clipped the top of the bar.
The Hoops had the ball in the net eight minutes later when Stokes fired past Kevin Stuhr-Ellegaard but the striker was judged to be offside when he collected Forrest's pass in the box.
Elfsborg's combative and pressing style gave Celtic very little time to settle in possession and they came close to a valuable away goal when Svensson's fierce strike from 20 yards was tipped onto the bar by the outstretched Forster.
Celtic started the second half in determined fashion and when Stokes picked out Samaras in the box with less than a minute gone it looked like the opener was coming but the Greek striker's weak effort was stopped by the 'keeper's legs.
Both sides upped the tempo and some hefty challenges led to a spate of bookings for both sides. Stefan Ishizaki was first to go in the referee's book before Johan Larsson was fortunate to avoid being shown red for a cynical challenge on Samaras while Emilio Izaguirre was booked for a foul on Bangura.
Time looked to be running out for the Hoops but Commons made the breakthrough when he stooped to connect with Izaguirre's cross and send a downward header past Stuhr-Ellegaard from close range.