Kieran Tierney is the one Arsenal player walking the disciplinary tight-rope if he is to feature in the Europa League round of 16 first-leg clash against Sporting CP on Thursday evening.
Squad rotation is expected from Gunners manager Mikel Arteta with this being his side's third game in the space of a week, not to mention they have a London derby away at Fulham three days later in what is an important fixture with regards to the Premier League title race.
Among the Arsenal senior players in contention to return to the starting line-up in Lisbon is Tierney, who hasn't started a Premier League game since the Boxing Day win over West Ham United as it has become apparent that Oleksandr Zinchenko is the first-choice left-back when fit and available for selection.
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However, that hasn't been the case in Europe so far this season as Tierney started all six group games - completing the full 90 minutes on three occasions - and scoring the winner against FC Zurich on matchday six that ultimately ensured the Gunners avoided a play-off knockout round tie.
With that said, taking the 25-year-old's disciplinary record into account, it might tempt Arteta to leave the Scotland international out of a Europa League starting line-up for the first time this season just to protect him.
As confirmed by the UEFA in their 'Regulations of the UEFA Europa League', players and team officials are suspended for the next competition match after three cautions, which did not result in a red card, as well as following any subsequent odd-numbered caution (fifth, seventh, ninth, etc.);
Currently, Tierney is the only Arsenal player in immediate danger of being handed a suspension as his yellow cards in the Europa League came in the double-header against PSV Eindhoven back in October, so he must watch his step at the Jose Alvalade Stadium. If booked against Sporting, he would miss the return leg at the Emirates Stadium a week later.
The Arsenal players on one yellow card across the squad are Gabriel Jesus, Gabriel Magalhaes, Gabriel Martinelli, Martin Odegaard, Thomas Partey, Bukayo Saka and Matt Turner. If any are booked against Sporting CP on Thursday, then they will be a suspension risk ahead of the second leg.
Granit Xhaka is the one player who has already served a suspension after being booked three times in the group phase, but as per UEFA rules, he would sit out a quarter-final tie - should Arsenal progress - if he was to be shown a yellow card in both legs against the Portuguese outfit.
In addition, it's worth pointing out that all yellow cards expire on completion of the quarter-finals and are not carried forward to the semi-finals.
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