Arsenal face a defining match this evening that could make or break their season, with the second leg of the Europa League clash against Benfica.
A 1-1 draw in the first match last week has left the tie delicately poised, though the Gunners hold a slight advantage due to their away goal.
Elimination from continental competition would effectively leave Arsenal with nothing to play for but pride in the remaining months of the season, with Mikel Arteta's side off the pace in the Premier League.
Securing a spot in the next round, meanwhile, would provide a timely boost and leave a path ahead for Arsenal to seal a spot in the Champions League next season by winning the competition.
With a lot riding on the game, it's understandable that emotions in the squad will be running high and that certainly appeared to be the case on Wednesday.
Arsenal's training session featured a one-touch rondo drill and David Luiz called out Kieran Tierney for using two touches during the exercise.
After words were exchanged, the Scotland international vented his frustration by booting a ball away in frustration.
The former Celtic man then took his place in the middle for the rondo, having broken the exercise rules, but wasn't done there as he then kicked the ball that was being used in the training drill away.
Tierney has only just returned to action following an injury layoff, making his return as a starter in Sunday's 1-0 defeat to Manchester City.
The 23-year-old is highly-rated at Arsenal, with many fans identifying him as having the potential to be a future captain for the club.
