51 min: News on Welbeck is that he has been taken to hospital for an x-ray.
48 min: Sporting raid down the left and send a deep cross over to Diaby, whose volley clatters into the arm of Jenkinson, who was just a yard away. No penalty.
47 min: Jenkinson essays a volleyed blaster from 30 yards, following from his wayward drive from a similar range in the first half. This one was even farther off the target. Third time lucky?
46 min: Let's go again before most of the Arsenal fans have regained their seats. Thy almost missed the breakthrough goal, but Aubameyang fired into the sidenetting after a cross by Mkhitaryan.
Half-time: Arsenal 0-0 Sporting
It's been dull. Penetrated but not been able to penetrate a disciplined but limited Sporting team. The victim could not be the same as the case for a serious injury to Welbeck. .
45 + 3 min: Aubameyang dinks over a tasty cross from the right. Lichtsteiner can not get a firm header on it.
45 + 1 min: Welbeck, most of it will be at least three minutes of stoppage time.
45 min: Mkhitaryan badly overhits his freekick from the right.
43 min: Sporting looked to be rare bits of possession until Mathieu played a sloppy pass in midfield. Mkhitaryan sprinted forward before being shunted to the ground by Acuna. Freekick to Arsenal wide on the right.
39 min: Lichtsteiner has a blast from long range and nowhere near the goal.
38 min: Guendouzi plays a lovely ball between two defenders to release Lichtsteiner down the right. The cross is the Swiss is cleared.
36 min: Ramsey, very involved in Arsenal's attacks, wins a corner, which is then taken short to him. But his cross is poor.
33 min: Sporting remain very disciplined as Arsenal continue to pass them around but not often through them.
29 minWelbeck is carried out from the field on a stretcher. The crowd chant his name and applaud loudly, Nani, Welbeck's former United Man teammate, who runs over to offer to the player, who clasps it appreciatively. No replay has been shown so it is hard to guess at what the injury might be – a damaged ankle seems most likely.
25 min: Lichtsteiner bends over a cross from the right. Welbeck produces another fine leap and sends his header from 10 yards towards the target. But it's a routine save for the keeper. And Welbeck hurt himself badly on the way down. Without a replay it's not clear what happened but he's in real pain. Stretcher-bearers have been summoned.
24 min: Arsenal continue to be dominated and are starting to find a groove that's bothering the visitors.
21 min: Nani beats two Arsenal defenders for old time's sake near half-way. Lichtsteiner, miffed, takes him out with a scissors tackle. The ref show the mandatory yellow card.
20 min: Freekick to Arsenal near the right-hand corner flag after Lichtsteiner fools to defender into a foul. Mkhitaryan's delivery is headed wide by Welbeck.
18 min: Guendouzi, after a one-two with Ramsey, fires over Mathieu, under pressure from Welbeck, sends it spinning towards his own goal from five yards. But a defender gets back to what it takes off the line!
17 min: another nice turn by Smith-Rowe, who sets off to sprint down the right. But Acuna chases him and gets the ball back.
16 min: Smith-Rowe shuffles his foot to the sky. Not what I meant when I suggested the game needs to take off.
14 min: This match has not been taken off yet. It's all very low key.
12 min: Mkhitaryan wriggles free in the box and tries to dig out a cross for Welbeck, but it's a fun behind for a corner.
10 min: Sporting attack down the right, Gasper giving Diaby a chance to outrun Jenkinson. He was too fast for his teammates, too, so I was not able to convert his low cross.
8 min: Iwobi releases Welbeck down the left with a fetching ball. Welbeck's cross is not so good. Arsenal take it short and eventually work it to Jenkinson, who tries to lash it into the top corner from 30 yards. It sails into the stands.
7 min: Jenkinson, raiding forward from left-back, sends a cross to the penalty spot but there's no one there to meet it.
5 min: Guendouzi is caught by two players. Sporting players. Sokratis manages to clear the danger. Moments later, at the end, Welbeck charges down an attempted clearance by the keeper, sending the ball out to the corner flag. So some early sluggishness at the back by both sides.
3 min: Nani's first involvement with him being tripped in his own half by Ramsey.
2 min: Arsenal have monopolized possession, but they are not inroads into the opposition, they are deployed in a good old-fashioned 4-4-2 formation.
1 min: Sporting, wearing an all-gray kit within five seconds.
The teams file out of the tunnel. They are greeted by the warmth of the fans and some boisterous chanting from the away section. The attendance looks to be close to capacity.
Other interesting results so far today: Rangers lost 4-3 at Spartak Moscow despite leading three times. Steve Gerrad's side did not even have a man sent off, for once. Elsewhere, Chelsea won 1-0 at Bate Borisov, Lazio beat Marseille 2-1 and Dynamo Kyiv tonked Rennes 3-1.
"A Portuguese born Londoner here," announces Tiago Marques. "Sportinguist since childhood and adopted Arsenal early on during my upbringing. Very good experience to witness to match the two teams I support! Would be lying if I said I had not been waiting for this for years now. Regardless, I just hope it's a cracker of a match! Win-win for me in the end. "Are you writing from the stadium? Are there many there like you? I'm guessing there must be at least a few. Enjoy!
Arsenal: Cech; Lichtsteiner, Sokratis, Holding, Jenkinson; Guendouzi, Ramsey; Mkhitaryan, Iwobi, Smith-Rowe; Welbeck
Subs: Martinez, Mustafi, Kolisinac, Maitland-Niles, Torreira, Nketiah, Aubameyang
Sporting: Ribeiro; Bruno Gaspar, Coates, Mathieu, Acuna; Nani, Gudelj, Miguel Luis, Bruno Fernandes; Diaby, Montero
Subs: Salin, Pinto, Jefferson. Dost, Mané, Cabral, Petrovic
Referee: G Mazelka (Lithuania)
Today's plan, as far as the second round of the Europa League as group winners by beating their closest rivals, Sporting. Arsenal have already been down in Portugal thanks to a goal by Danny Welbeck, who have become the most successful head-to-head record. Then they could field even weaker lineups for their two remaining group games if they were wanted, but it would be a shame to be frittered away an epic unbeaten record if it is still intact by then – they could stretch it to 15 matches today.
They are losing today in their national league. Vorskla and Qarabag. Despite their staunch European pedigree, they are also in the north-east of the country, where they are beaten Newcastle and Middlesbrough (they're also knocked Sunderland out of the 1973 Cup Winners' Cup despite losing at Roker Park) so maybe it's about time.