Hector Bellerin has not travelled to Bulgaria for Arsenal's game against Ludogorets but Arsene Wenger expects to have his right back available for the derby against Tottenham.
Bellerin suffered what a club source described as a 'minor knock' at the end of the training session before the team's flight to Sofia.
Wenger decided to leave the Spain international out of the squad as a precaution but it is not thought to be serious.
The Arsenal boss has taken no risks with the Spurs game at the Emirates Stadium looming on Sunday.