The second factor is Napoli at home, on occasions they can be formidable as some of their home results this season have shown.
Arsenal now head to Naples next week looking to reach the last four for the second year in a row and Emery was pleased with another strong showing from his side.
An Aaron Ramsey effort and a Kalidou Koulibaly own goal gave Arsenal a 2-0 victory over Napoli in the first leg of their Europa League quarterfinal on Thursday - and a rare and valuable clean sheet to take to Italy in a week's time. With the FA Cup final looming, Watford will most likely shift their attention away from the Premier League and we might see some of the top players getting some rest in the remaining league matches.
Emery admitted on the eve of the tie that his side needed to win at home, given their poor form on the road this season.
"I think that the second half was completely different", Ancelotti said. In the first half we were consistent and we didn't concede good chances to them, but they scored from one throw-in, unfortunately for us.
"We are confident. We had a good result and we have everything in our hands".
"In the second half we had their measure and there was more control on the game".
"I was surprised by the lack of courage and personality from my players initially", he said.
"I think they have nearly got to be on the front foot in Naples". Rarely did the visitors play through Ramsey or Torreira but because the midfield pair pressed high, Arsenal's back three had to no choice but to squeeze up too, leaving space for Napoli to take the direct route.
Both goals came from pressing Napoli either side of the halfway line and breaking at break-neck speed once possession was won. "That will be great for us".