Crowd trouble during Everton's Europa League victory over Hajduk Split at Goodison Park on Thursday night is set to be investigated by UEFA.
Trouble flared in the 33rd minute of Everton's 2-0 win in the qualifying play-off first leg, with missiles thrown and advertising boards kicked over as supporters surged towards the pitch.
As stewards and police moved to try to bring the situation under control, the players were instructed to leave the field by Slovakian referee Ivan Kruzliak and the game was halted for several minutes.
Hajduk Split players approached their travelling fans and appeared to appeal for calm. The match got back under way after a break of nearly five minutes.
Merseyside Police revealed on Friday morning that one man was detained for pitch encroachment and is likely to be summoned at a later date.
They will hold a normal post-match debrief in conjunction with the club and will decide then if further action is to be taken.
Michael Keane's header had given Everton the lead just prior to that in the 30th minute and Idrissa Gueye doubled the advantage in the 45th minute after play resumed.
Regarding the crowd trouble, Toffees boss Ronald Koeman said: "I was disappointed. I like to have it really fair, that you can play football, and we needed to stop. I don't know what happened, it was in the corner."
Koeman was also unhappy with his side, having felt they failed to take a "big opportunity" to effectively seal qualification for the group stages ahead of next Thursday's second leg in Croatia.