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 goalkeeper 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 them into the lead in the 76th minute.
It means the Scottish champions will only take a slender advantage to the Boras Arena, where Elfsborg have not 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.”
Celtic had named an unchanged line-up to the one that saw off Cliftonville last week as they looked to make home advantage count.