Charles Watts, the Arsenal reporter for Football.London, gives us the inside track on Saturday's opponents
We've had our fair share of problems in the centre-half department but it looks like the curse has spread over the fence?
"Yes, Arsenal have got a few issues at the back. Mustafi got injured on international break and it looks like a bad one. We're not sure about Koscielny yet. He's been managing an Achilles problem, a chronic one which he'll have to manage for the rest of his career. It flared up before the international break and Arsenal are hoping to be able to guide him through.
"If he's missing, then it's something of a defensive crisis as the defence revolves around him. If he's back and they manage to patch him up they should be able to cope without Mustafi, as Koscielny will just slip into the centre of a back-three. Having said that, Mustafi has been putting in a few good performances recently and has looked much better on the ball.
"If Mustafi and Koscielny are out they'll have to bring in Holding and Mertesacker, and they've not played much between them. Watford will fancy their chances of causing problems at the back if those two play."
Things are not plain sailing further up-field either, are they?
"Ozil and Welbeck are major doubts. They are looking more at the Everton game for Ozil while Welbeck was supposed to be back training on Monday, with Ozil, and there is a hope he might be available. Kolasinac also came off at half-time during Bosnia's game against Estonia so we'll have to see how he is. He's already a real fans' favourite."
Arsenè Wenger seems to like the 3-4-2-1 formation. How did he stumble across that?
"It came about after the dreadful defeats last season at West Brom and then Palace, where they looked awful. The rot started against Watford at the Emirates and they just had a nightmare spell after that, culminating in the defeat at Palace. Something had to change; they needed a new focus, a change of system and a change of routine. They finished the season by winning 10 of the last 11 and winning the FA Cup."
Sadly, the momentum didn't continue into this season, did it?
"They had a bad start to the season, and there were lots of reasons behind that, mainly because the summer didn't pan out as Wenger wanted and because there was so much uncertainty over who was staying. But they've kept five domestic clean sheets in a row now, won six of their last seven in all competitions and look like a more balanced team. They seem to have put their issues behind them now."
Was the 4-0 hiding at Liverpool in late August something of a watershed moment, as you've not lost since then?
"It was. There was so much uncertainty that day as it was the day before the transfer window shut. You had both Oxlade-Chamberlain and Sanchez wanting to leave and it just all culminated in an absolute horror show. Wenger must take most of the blame for that day. How he picked the Ox, when he told him the day before he wanted to leave, is still beyond me.
"He left Kolasinac and Lacazette on the bench and played Bellerin out of position on the left to accommodate the Ox. It was all very strange. But they got it out of their system, got rid of the Ox, Sanchez stayed and all the uncertainty went. The results have picked up since."
It was no secret that Alexis Sanchez wanted away. Has he thrown his toys out of the pram or has he knuckled down and got on with it?
"He's been okay, to be honest. Before the international break the second-half against Brighton was the best he's played this season. He looked hungry, provided a good assist for Iwobi's goal and scored a great goal against Cologne in the Europa League. He's not at the level he was last season and is still searching for full fitness, but the signs are more promising. We'll just have to see what sort of mindset he's in when he comes back from international duty as Chile didn't qualify for the World Cup."
Ozil is another Arsenal player in the last year of his contract. Has he played like someone who wants a new one?
"He's been out for ages and has barely featured because of what Arsenal are saying is a knee injury. The signs are that he was going to be involved this week but I can't imagine he'll start. He's very much in the background at the minute and is almost the forgotten man. Fans are hoping he performs well in the last year of his contract."
There was talk this week of Jack Wilshere seeking a move to boost his World Cup chances. Is he in Wenger's plans?
"He's not likely to start on Saturday. He's very much part of the second string who play in the Europa League and sit on the bench for the Premier League games. He'll be on the bench on Saturday as Xhaka and Ramsey are very much first choice and then you've got Elneny and Coquelin behind them. There are plenty of games coming up for Wilshere to try and force his way into Wenger's Premier League plans."
What's the feeling around Wenger right now? Can we expect planes carrying banners to be flying over Vicarage Road on Saturday?
"They've settled down a bit because they are winning, but they are only ever one defeat away from being in crisis again. There is no doubt Wenger's lost a section of the fanbase. Most fans would be worshipping the manager if they'd won the FA Cup three times in the last four years but that's not the case at Arsenal. There are a lot who want him to go and we are only ever one defeat away from the Wenger Out brigade resurfacing but, for now, the ship is settled and, touch wood, let's hope that continues."
The Gunners seem to like playing at Vicarage Road, scoring three in each of the past two seasons and playing some dreamy football in the process?
"It seems to be one of the grounds they perform well at for whatever reason. Perhaps it's because they don't have far to travel and the fact they always get big support at Vicarage Road. Even though Watford are a strong, powerful side, and they'll have to deal with the physical battle, they've got to fancy their chances. They're playing well."
We believe we are a different proposition to the side you faced in 2015 and 2016. How are we being viewed from across the fence at London Colney?
"You've done very well. Every year you expect it to go wrong with the chopping and changing you do but, again, the team copes with it very well. You've had a very good start to the season and have caused every team problems. You look strong, well drilled, physical with some real quality in the side. Marco Silva is a very impressive manager and I think you'll have a very decent season."