The prospect of a London derby in this season's Europa League moved a giant step closer after positive results for Arsenal and Chelsea in the first legs of their semi-finals.
Arsenal bounced back from the early concession of an away goal to beat Valencia 3-1 at Emirates Stadium, while a valuable Pedro goal in Germany handed Chelsea at advantage as they secured a 1-1 draw against Eintracht Frankfurst.
Alexandre Lacazette and Pierre-Emerick Aubameyang hit the goals for Emery's side and despite a late third goal from the latter of the striking duo, he insists the tie against his former club is evenly balanced heading into the second leg.
"The tie is 50/50. We know how tough Valencia will be in front of their fans next week," stated Emery. "All our players did well. I am very proud of all of the players, our supporters and of our work. The second leg will be difficult.
"We found it hard to break them down. Marcelino normally plays with a 4-4-2. It was a very good game. It was different to how we expected it to be and now we have to ready. They are very strong in front of their fans.
"I want to enjoy playing in Valencia I want to enjoy with our team, our players, our supporters. The atmosphere will be very tough over there."
Sarri surprisingly opted to leave star man Eden Hazard on the bench for his side's trip to Germany, as he insisted his Belgian play maker was jaded.
"Eden was on the bench because, in the last period, he played 10 matches in a row," said Sarri. "It's impossible to play that many.
"For us, this was match No59 I think, and Hazard also played eight matches in the national team. For a player, it's impossible to play 70-75 matches in a season. And so, sometimes, Hazard like all the other players needs to rest. Or not to rest, but not to play for 90 minutes.
"This is the first reason. The second is that Eden usually is able to change the match from the bench, and so, for me, it was better to start with Willian and then to try, in the last 30-35 minutes, with Eden. But for Eden, it's impossible to play 75-80 matches in a season.
"He was in the dressing room joking as usual, as normal. But he knows the truth very well. He knows very well that sometimes he has to rest. For a player that has to play 70 matches in a season, it's normal. A normal reaction."
Sarri insisted his efforts to secure a top four finish in the Premier League are as important as his Europa League ambitions, ahead of Sunday's game against Watford.
"We have to play five matches in two weeks with the same level of importance," he added. "We don't know at the moment which is the right way (to qualify) because we can get into the Champions League by the Premier League or by the Europa League.
"At the moment, we don't know the right way. But we want both. We want the top four in the Premier League, and we want to reach the final. But we don't want to play the final this time; we want to win the final.
"It's very difficult because we have to play again in the Premier League in 62 hours, so it's not easy to recover, especially in a very competitive championship like the Premier League. You risk to pay."
The results of the first legs of the semi-finals bring the prospect of the two London clubs making a long journey to Bacu in Azerbaijan later this month.