Danny Welbeck suffered a serious looking ankle injury as Arsenal advanced to the knock-out stages of the Europa League with a 0-0 draw against Sporting.
It was a hugely frustrating night for the Gunners but the result was enough for them to come through a rather unchallenging group stage so far.
Welbeck's injury will no doubt overshadow that achievement, though, as the north London side failed to score for the first time since the opening day of the season.
Story of the match
The reverse fixture two weeks ago in Lisbon was one which started slowly and it was the same story again a fortnight later.
The Gunners starting XI was much changed from the match with Liverpool and it showed with attacking fluidity lacking. The sprightly teenager Emile Smith Rowe looked lively early on, though, drifting between the lines. He had Arsenal's first shot, skipping away from his man but firing off target after 16 minutes.
That was only a half chance and it appeared to set the scene for what was to come, with both Arsenal full-back's Carl Jenkinson and Stephan Lichtsteiner also shooting wide during the first 45 minutes.
The closest Arsenal had come to opening the scoring came courtesy of a Sporting player as a ball in from Matteo Guendouzi deflected off Jeremy Mathieu before being cleared off the line by Sebastian Coates.
It soon became a match which was to be overshadowed by a horrible injury to Welbeck. He got up to challenge for a header from Lichtsteiner's delivery from the right and appeared to go down rather innocuously.
The forward immediately looked in distress, though, and so did his team mates in close proximity. Arsenal's medical team responded quickly with Welbeck receiving oxygen before having his right leg heavily supported as he was stretchered off, being replaced by Pierre-Emerick Aubameyang.
The second half was much of the same but Aubameyang was to come close on a few occasions, firing off target twice and also seeing an effort blocked well after good work from Sead Kolasinac on the left.
It wasn't a great night for Arsenal who would suffer another injury three-quarters of the way through the match as Lichtsteiner was forced off with a pulled muscle.
Unai Emery's team have usually come to life in the second 45 minutes of matches this season but that wasn't the case on Thursday night as a clear cut chance never arrived.
Mathieu had been exceptional at the heart of the Sporting defence but was to be sent off late on for a last man tackle on Aubameyang. The Gabonese international's free-kick from the edge of the box was then wayward and rather summed up the night's dull proceedings.
Takeaways
Mkhitaryan and Ramey struggle
Tonight was a big opportunity for Aaron Ramsey to display why his new contract shouldn't have been withdrawn. But it was a performance in his natural central midfield position which didn't show any signs of a player warranting big money to keep him at the club. He struggled to control the game and when Arsenal needed a creative spark he failed to provide it.
The same can be said for Henrikh Mkhitaryan who is particularly struggling this season. His performances in most matches have been hugely inconsistent and this was another average display from the Armenian. He found space in promising areas but rarely created chances for his side.
Sporting get tactics spot on
The Portuguese side were solid enough in Lisbon two weeks ago but in London they were even better. As expected they set up to defend for the majority of the game and they did so tremendously. They created next to nothing going forward but frustrated Arsenal with an organised defensive performance which made them difficult to break down.
Perhaps with the likes of Mesut Ozil and Alexandre Lacazette, the Gunners may have fared better in the final third.
Stand out players
Sporting's centre-half pairing of Coates and Mathieu were brilliant on the night. The latter's red card came too late in the game to really influence proceedings but up until that point they hadn't put a foot wrong as they kept a clean sheet against a free-flowing Arsenal attack.
Rob Holding showed that it was more of a night for centre-halves by putting in another mature performance among the Gunners backline in a match which lacked any quality. Guendouzi showed some nice touches as he has done this season whilst Kolasinac was arguably Arsenal's best player once he came on.
Ultimately, no one found the sufficient quality to separate the two teams as Arsenal and Sporting remained deadlocked at the Emirates.