Fans invading the pitch to try to take selfies with players is "a concern", said Portugal manager Roberto Martinez after his side's victory over Turkey at Euro 2024.
Five people made it on to the pitch to try to take photos with Portugal captain Cristiano Ronaldo in their 3-0 win in Dortmund.
Security guards at Westfalenstadion had to chase after each supporter while players and fans in the stands grew increasingly frustrated.
"It is a concern. Today the intentions of the fans were good. We all love a fan who recognises the big stars and icons," said Martinez.
"But you [must] understand there’s a difficult moment if their intentions are wrong. We need to be careful. It shouldn’t happen - there’s a lot of security.
"We should give a message to the fans also because it is not the right way. It may get worse for the future. It’s not good to have the players so exposed on the pitch."
The first supporter to break on to the pitch was a young boy and Ronaldo gave him a hug before smiling for a photograph.
But Ronaldo was annoyed when the third person tried it while Portugal were preparing to defend a corner in the second half and security guards had to restrain the fan by the side of the goal.
At full-time, Ronaldo pushed away a fifth supporter and was escorted off the pitch by a member of security.
However, Portugal team-mate Bernardo Silva said he was "personally not really concerned" by the pitch invasions.
"It’s just a bit annoying in terms of always having to stop the game because a fan enters the pitch," said Silva.
"I think that’s the price you pay for being so recognised in the world of football and having a player like [Ronaldo] with us in the team. But in terms of being in danger, no I don’t feel that personally."
Ian Dennis, BBC Radio 5 Live's senior football reporter on commentary, said "questions will be asked of the security".
"The security here has been lacking and this stadium will host a semi-final - they're going to have to tighten it up," he added.
Uefa's disciplinary body will await reports from officials before deciding any action going forward.
