Liverpool were unable to break down Atletico Madrid on a frustrating night at the Wanda Metropolitano.
The Reds were condemned to a 1-0 defeat as they failed to overcome Saul's early strike in their last-16 first leg.
One of their most creative sources this season, Trent Alexander-Arnold, attempted to utilise his passing range and precise right foot to find a way through Diego Simeone's organised side.
He often moved centrally and more advanced as as the game progressed and Liverpool dominate possession.
But his impact was limited with no way through the home side - and Rio Ferdinand felt Simeone's side pinpointed Alexander-Arnold's threat.
He highlighted how they quickly pressed the full-back and closed off any passing lanes through the middle of the pitch to limited his influence.
"This is Atletico. This is what we know Diego Simeone's teams set up like," Ferdinand said in the BT Sport studio.
"They are compact, they are tight, they are diligent in the way they defend, they get out to people really quick.
"Trent Alexander-Arnold today, every time the ball has gone out to him, they get out there quickly. They know how dangerous he is with the ball.
"Anything through the middle of the pitch they are not allowing."
After the game, defender Virgil van Dijk revealed how manager Jurgen Klopp told his side to "keep playing" during his half-time team-talk.
Van Dijk told BT Sport: "We conceded the goal from the corner, first chance for them, not even a chance. Bit of luck.
"The message at half time was to keep playing. We had the ball most of the game but unfortunately could not create massive opportunities. We still have another 90 minutes to set it right.
"It is the way they play. It is a bit of the Spanish football as well and you have to adapt but we knew it and I feel we handled it pretty well."
