The Glasgow giants again had the chance to put the Panthers under pressure in the 20th minute, but Thompson’s inviting free-kick evaded all his team-mates in the area.

Avalos was the next man to go down theatrically after a clash with Neil Lennon, but justice was done when Pedrosa fired high over the bar from 25 yards.

The Boavista player again ambitiously chose to go for goal with his next free-kick, but again he blasted into the netting behind the goal from 32 yards.

Pedrosa was again off-target from 27 yards after Johan Mjallby had dangerously given the ball away in his own half.

The officials failed to spot a late challenge from Silva on Balde, but the the defender’s decision to get to his feet immediately took the sting out of the incident.

Boavista’s first real threat came in the 33rd minute which hesitancy from goalkeeper Robert Douglas made the situation a lot worse than it should have done.

Martelinho found Santos down the right flank and he fired across the face of goal, but despite no team-mates in support Mjallby had to head the ball away to safety.

But a minute later Celtic suffered a blow when Lambert was forced hobble off after the earlier collision with Silva and Sutton came on much earlier than he expected.

Boavista seemed to grow in confidence from that and Santos’ 20-yard right-foot strike curled wide of Douglas’ upright from Duda’s pass in the 37th minute.

But the Celtic keeper denied the home side the opener just two minutes before the break when Silva got on the end of Martelinho’s cross, but his header was pushed away by the Scot.