The Brazilian was very pleased with his side's 5-3 aggregate win over PSV, and praised Los Che's defensive work in the second leg of the tie
The Spanish outfit recorded a 4-2 win in the first leg and held the Eredivisie club to a 1-1 draw in the return in Eindhoven on Thursday, much to the delight of the Brazilian.
"We worked really well defensively, and in attack we did tremendously. PSV are a very good side, and with those fans behind them they are tough opponents," Diego Alves told the official Uefa website.
"During the game they got stronger and stronger which made it a very difficult night, and I'm happy to have qualified."
The 26-year-old shot stopper played a key role in his side's success with some crucial saves, and was pleased with his individual performance.
"When an opponent is on the attack, you prepare yourself for the idea that the cross might be delivered well and when the header comes in you simply throw yourself at the ball.
"I managed a good save and it helped the team that we went in at the break without conceding. That pleased me."
The draw for the Europa League quarter- and semi-finals takes place in Nyon, Switzerland on Friday at 13.00CET.