Newcastle remained resolute for the remainder of the first half, but the breakthrough finally came seven minutes after the interval when Fabricio Coloccini inadvertently turned Alex Oxlade-Chamberlain's shot into his own net.
Here, Sports Mole takes an in-depth look at whether the result was a fair one.
On target: 0
On target: 9
Was the result fair?
Absolutely. There may not be a more one-sided game this season than today's match, with Arsenal completely dominating from start to finish. The statistics above demonstrate just how in control the Gunners were, with Petr Cech not being forced into a single save, while at the other end Tim Krul had a number of stops to make. Newcastle spent the vast majority of the match chasing the ball and, when they did get it back, they didn't hold on to it well enough to halt the relentless pressure on their defence.
Many fingers will be pointed in the direction of Mitrovic for landing his side in it with that early red card but, while that certainly did not help their cause, the truth is that Arsenal already had a degree of control before the striker was sent off. They enjoyed more than 70% possession when it was 11 vs. 11, and it was more of the same with a man advantage. Even so, Newcastle would have been able to be a little more adventurous had they stayed with a full complement on the field.
The disappointing thing for Arsenal will be that they only managed to win by the one goal. With such total dominance, they will feel that it should have been more comfortable for them today. They never looked in danger of conceding at the other end of the field, and it always felt like a breakthrough would arrive, but the fact that it came through an own goal rather than any particularly good play from his own team may worry Arsene Wenger a little.
Questions were asked regarding Newcastle's heart, hunger and desire under John Carver last season, but they certainly weren't lacking in those areas today. In many ways, it was a very similar match to the one against Manchester United last week, with the Magpies on the back foot early on but defending their penalty area for their lives. Krul was once again impressive, while the whole defence deserves credit for limiting Arsenal to just the one goal despite wave after wave of attacks.
The area they did lack in was discipline, and that will be a major concern for Steve McClaren. The fans gave referee Andre Marriner a lot of stick throughout the match, but the only decision he got wrong actually went in the home side's favour. The red card was deserved, and by the end of the match they had had a further six players booked. There was a spell shortly after the dismissal when they appeared to have lost their heads, and a second red card at that point looked inevitable.
The performance, from a defensive standpoint, will contain lots of positive for McClaren. They once again put in a really stubborn display at the back, and that in turn got the crowd on their sides. McClaren made a big point of telling his players to go and applaud the fans, who turned St James' Park into a very hostile environment this afternoon. In terms of attack they offered nothing at all, but the desire shown from many of the players will please the fans. Ultimately, though, it is now four games without a win in the league, and McClaren will be desperate to get that first victory under his belt.
It is another three points, and a second consecutive clean sheet for the Gunners, but they won't be entirely pleased with their performance today. They were the only team in it from start to finish, but Newcastle were able to frustrate them and once again questions over whether they need a striker will be raised. Theo Walcott was given a chance up top today, but he squandered two really good chances and certainly didn't look like a player who could fire the Gunners to the title - although in fairness the red card probably hindered his game as Newcastle defended deeper and deeper, leaving no space in behind.
The statistics tell the story, though - 74% possession and 22 shots, yet they only managed to score through a deflected own goal. It means that, of their three goals so far this season, two have been scored by opposition players. There is no doubt that they deserved to win this match, but for a while it was questionable whether they had what it took to make the breakthrough. Considering how dominant they were, they didn't create as many clear chances as they might have hoped.
It is hard to draw too many conclusions from a match like this as it was so one-sided, but that cutting edge did appear to be lacking for the Gunners. Staying 11 vs. 11 may have actually favoured them in that there would have been more space to operate in, instead of Newcastle getting everyone behind the ball. Some of the football they played was nice, and defensively there were none of the shaky moments that happened against Liverpool, but Wenger will know that improvement is still needed.
Sports Mole's man of the match
Tim Krul: For the second consecutive week Newcastle put in a fine defensive performance, and central to that was Krul. The keeper was called upon to make a string of saves to keep Arsenal at bay, and he didn't deserve to be on the losing side today. He was desperately unlucky with the winning goal too.
This one has to go to Mitrovic for his silly red card. In fairness to the striker, there didn't appear to be any malice involved in his high tackle on Coquelin, but his studs were showing and he did plant them right on the shin of the Arsenal man. Some may feel that the red card was harsh, but you can certainly see why the referee gave it.
Marriner won't have many tougher games than this. St James' Park was like a bear pit today, with the fans letting the referee know exactly what they thought of his decisions. However, with just one exception, he got all of the big calls right and ran the game with a degree of common sense too. The red card was the right call, while there were a number of other questionable challenges from Newcastle during that period that he dealt with well.
The exception was a penalty shout for Arsenal early on, when Florian Thauvin clipped the heels of Hector Bellerin inside the box. There was clear contact between the two players that sent them both tumbling to the ground, but Marriner waved it away. It looked like a stone-waller in normal time, and the replays confirmed that a spot kick should have been given.
Newcastle: Newcastle will renew their search for a first league win under McClaren when they take on West Ham United after the international break.
Arsenal: Arsenal, meanwhile, host Stoke City at the Emirates next.