Arsenal booked their place in the knockout phase of the Europa League with two games to spare following a goalless draw against Sporting Lisbon at the Emirates on Thursday evening.
The night will largely be remembered though because of a serious ankle injury sustained by Danny Welbeck which saw him stretchered from the field during the first half.
His replacement, Pierre Emerick-Aubameyang struck the crossbar early in the second half but that was as close as the Gunners came to a winner as Sporting, who had Jeremy Mathieu sent off late on, held on for a point.
The draw was enough to see Unai Emery's side, who extended their unbeaten run to 15 matches, through to the last 32 because of Qarabag's 1-0 win at Vorskla but they will have to wait until their next match - a trip to Vorskla on November 29 - for the chance to seal top spot in Group E.
After a relatively quiet start in north London, the game burst into life when Matteo Guendouzi's low cross was almost turned into his own net by Mathieu, but with the ball trickling towards goal Sebastian Coates hooked the ball to safety.
Arsenal were then dealt a huge blow when Welbeck fell awkwardly after going up for a header against Bruno Gaspar. The 27-year-old, who has had his fair share of bad luck with injuries over the years, was eventually stretchered from the field with his team-mates visibly shaken by the extent of the injury.
Welbeck was replaced by Aubameyang who nearly broke the deadlock minutes into the second half, getting across his man to meet Henrikh Mkhitaryan's low cross, but the striker's shot clipped the top of the crossbar.
Sporting rarely threatened the Arsenal goal but in the 58th minute they served up a reminder as former Manchester United winger Nani burst past Aaron Ramsey and into the Gunners' half. He pulled the ball back from the byline in search of Fredy Montero but Petr Cech read the pass, diving off his line to gather ahead of the striker.
Arsenal suffered a further injury blow when Stephan Lichtsteiner pulled up with a suspected hamstring injury and he was replaced by Ainsley Maitland-Niles with 17 minutes remaining.
The Gunners pushed for a winner but the game continued without any real chances of note, Mkhitaryan stabbing an
Alex Iwobi cross towards goal before Aubameyang saw an effort bravely blocked.
Aubameyang thought he had a late one-on-one to win it but was fouled by Mathieu, who was shown a straight red card for the cynical trip. Aubameyang fired the resultant free-kick over the crossbar as Sporting held on.
Opta stats
- Arsenal failed to score for just the second time under manager Unai Emery, also drawing a blank against Man City in the Spaniard's first game in charge (0-2).
- Sporting CP failed to have a single shot on target in either of their meetings with Arsenal this season.
- Excluding qualifiers, Arsenal have kept three consecutive clean sheets in European competition for the first time since the 2007-08 Champions League group stages.
- Sporting kept their first away clean sheet in the Europa League since September 2011 (2-0 vs FC Zurich), ending a run of 18 games in which they'd conceded.
- Pierre-Emerick Aubameyang had twice as many shots as any other Arsenal player (4), but not a single one of these was on target.
The managers
Unai Emery: "It's the worst news tonight, this injury. It's clear that we are with Welbeck in these minutes.He was working well and he was having a good match. He had some chances too.His injury was with the mentality of the players. They saw it was a big injury. When you are playing football, when you are playing in competitive matches, it can happen. You don't want it to happen but this is our profession. Now he is at the hospital. The news is that we are going to wait - but we think it's a serious injury."
Tiago Fernandes: "The players did exactly what I asked them to do. In our game plan we know we had to be rigorous and they were almost perfect on that. We were aware of the opponent's quality but we, knowing our capacity and being creative and aggressive with and without ball, could try to surprise here."
Man of the Match - Sebastian Coates
It proved a frustrating night for the Gunners and the former Liverpool and Sunderland defender played a big part in that.
He kept his side in it with a goal-line clearance in the first half after Mathieu diverted Guendouzi's cross towards his own goal line.
He then put his body on the line during the second to make an excellent block to deny Aubameyang and help his side to a crucial point at the Emirates.
What's next?
Arsenal are back in Premier League action on Sunday when they take on Wolves at the Emirates Stadium (4.30pm). Next up in the Europa League is a trip to Ukraine to take on Vorskla (November 29, 5.55pm).
Sporting are back in domestic action on Sunday hosting Chaves in the Primeira Liga (8pm). Their next Europa League match is a trip to Azerbaijan to face Qarabag (November 29, 5.55pm).