The £10.5m midfielder returned to action on Wednesday night in the reserves' 1-0 defeat by Leeds at Wrexham. It was his first run-out since having his ankle broken by Frank Lampard's tackle on New Year's Day at Anfield.
Alonso was a surprise inclusion in the squad which beat Juventus 2-1 at Anfield in Tuesday's first leg, but boss Rafael Benitez said at the time: "If we need to use him, things have gone wrong.
"He is probably two weeks away from a proper level of fitness."
Alonso told the club's website: "It was good for me to have a game and I felt no pain. I have been out for three months and it has been very frustrating to miss out on some very big games.
"I am getting fitter and I hope to be back in the first team soon. I am very confident, the ankle is good and I am running very well."
Great news and I loved the reception he got while warming up tuesday n8.
