PSG won the first-leg of their semifinal 1-0, thanks to Ousmane Dembele's fourth minute strike, with Partey missing the game due to suspension.
Parlour told Tribalfootball.com: "Arsenal missed Thomas Partey’s presence in the centre of midfield. They struggled to cope early on with the way PSG pressed and won back possession quickly. After conceding such an early goal, Arsenal had to adjust their football, which they did and credit to Mikel Arteta, they created a couple of good chances and on another day draw or win the game."
Parlour admits the Gunners struggled defensively in midfield.
He continued: "The closing down throughout the game should have been better, I think they gave PSG too much respect and as mentioned, Partey was a big miss as it meant Declan Rice’s game changed and also (Mikel) Merino’s game too. Merino has been doing a good job as the number 9 which worked well in both Madrid games.
"I thought he played well last night, unlucky with his goal being ruled out. Two very good saves by PSG keeper from Martinelli and (Leandro) Trossard which kept Arsenal from scoring on the night. I was impressed with (Ousmane) Dembele and (Khvicha) Kvaratskhelia and also Vitinha had an excellent game.
"If you look at Arsenal’s team, you are missing the spine of the team in Gabriel, Partey and (Kai) Havertz, but they will have Partey back next week, who can get Arsenal having more control of the game.
"Arsenal had a lack of real attacking options off the bench last night and this is where they will look to add to their squad over the summer with more quality in that area. But overall, Arsenal are still in the tie, it’s only a one goal lead for PSG."
How Arsenal can win in Paris
PSG were able to control possession and play the home crowd out of the game. Parlour, however, says things could be different in Paris thanks to Partey's return from his ban.
He said, "Arsenal got into the game after around 20 minutes in the first leg and with Partey back, it’s so important Arsenal win the midfield duels and get on the ball. Scoring first in Paris is vital for Arsenal and in (Bukayo) Saka and (Gabriel) Martinelli, they have the tool to do this. Merino as number 9 will also help and he can cause PSG problems.
"It’s not over, but it’s key that Arsenal don’t concede early and can grow into the game in Paris. You look at Arsenal’s away record in Europe this season and it is pretty good. Winning in Madrid and heavily against PSV. They have nothing to fear and also from set pieces Arsenal can look to capitalise.
"It’s a very tough ask, but providing Arsenal can gain some control of the game in midfield, stop Vitinha dictating the game, then they can create chances to score. Being clinical is key as well. There won’t be loads of chances, so the one’s Arsenal can get, they have to look to score from."
- Ray Parlour was speaking to Tribalfootball.com on behalf of NetBet Sports Betting