Linfield will investigate an incident where a bottle was thrown at Celtic striker Leigh Griffiths during his side’s 2-0 Champions League second qualifying round win at Windsor Park.
Griffiths delayed taking a second-half corner to pick up the bottle and was booked by referee Alejandro Hernandez.
Manager Brendan Rodgers said the officials “could not explain” the yellow card.
Celtic did not take up their ticket allocation because of security fears.
But there were about 300 travelling fans inside the half-full ground to see first-half goals by Scott Sinclair and Tom Rogic secure a first-leg victory for the Scottish champions.
“It happens [missiles being thrown] in other grounds, it’s not just here,” Rodgers said. “It’s not ideal in any situation. You don’t want that to happen in any ground.
“It was strange him getting booked for it.”
‘The pitch should be a safe environment’
Objects had been thrown at Griffiths earlier in the game while taking a corner and substitute Jonny Hayes was also targeted.
Linfield chairman Roy McGivern walked down to that area of the stadium, but his intervention failed to prevent further incidents.
After the final whistle, some Linfield fans attempted to invade the pitch when Griffiths tied a scarf to the goal posts.
“The club will be reviewing our own footage and investigating,” read a Linfield statement.
“We are obviously very disappointed that a small number of people chose not to respect the club’s wishes. There will be serious and lasting consequences for anyone involved.”
Asked whether he was concerned during the game, Rodgers said: “I didn’t see or haven’t heard as of yet what was thrown on. I could only see it from the dug-out.
“It was maybe a bottle of some sort, but anything, whether it’s a coin or a bottle or whatever, shouldn’t happen.
“Players go on to the field and it should be a safe environment for them. You want the passion from the stands to stay in there. But if you take that away from it, it was a good evening.”
‘Roy made some incredible saves’
Celtic were comfortable victors as they looked to set up a third qualifying round meeting with either Norwegian champions Rosenborg or Irish title winners Dundalk.
Last season’s Scottish PFA player of the year Sinclair headed them in front after 17 minutes before Australian Rogic guided in a second five minutes later.
They might have added to that tally, had it not been for 39-year-old former Manchester United and West Ham United goalkeeper Roy Carroll.
“I thought Roy was brilliant, he made some incredible saves,” said Rodgers.
“It could have been a really difficult game for us but in the main we dealt well with it. They can be tricky ties. But the players came through it.”