Arsenal defenders William Saliba and Takehiro Tomiyasu have both been forced off during the Gunners' Europa League game against Sporting.
Arsenal are currently at the Premier League summit, some five points clear of their nearest challengers Manchester City.
Indeed, the north Londoners are just 11 games away from claiming their first league title since 2004.
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However, Mikel Arteta's men are fighting on two fronts, with the club also competing in the Europa League last-16 against Sporting.
In the first half of their second-leg encounter against the Portuguese giants, Arsenal were dealt a double injury blow that could have wider implications on the Premier League run in.
Arsenal's double injury blow
Tomiyasu required treatment following an awkward slip just eight minutes into the first half. After a long pause in play the Japan international trudged off and was substituted for Ben White.
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Ten minutes later, Arsenal were forced into another enforced change, as Rob Holding replaced Saliba.
The France international followed Tomiyasu down the tunnel appearing to have a back issue.
The loss of Saliba for any prolonged period of time could have implications on the Gunners' title ambitions. The 21-year-old has been a revelation this term, forming a stubborn partnership at the centre of defence with Gabriel Magalhães.
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Arsenal have continued their imperious form despite having been dealt a series of injury blows. The likes of Gabriel Jesus, Emile Smith Rowe and Mohamed Elneny have had extended periods on the sideline, while the likes of Thomas Partey and Kieran Tierney have also spent time in the treatment room.
Meanwhile, Eddie Nketiah is currently out.
Given Arteta has rarely had a clean bill of health this term, Manchester United manager Erik ten Hag baffled Gooners this week by claiming Arsenal's success was partly down to their lack of injuries.
The Dutchman said: "Man City home [2-1 victory in January], it was the only time this season [that United had a fully fit squad], in other times, every time, every game is a player suspended, injured, illness. So we have to deal with it well, of course, you hope.
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"I see Arsenal, they almost have all the time a squad that is totally available."
Topics: Arsenal, William Saliba, Mikel Arteta, Sporting CP, Premier League, Europa League