Jurgen Klopp revealed that Curtis Jones was initially a doubt before he starred in Liverpool's 5-1 win in Porto.
The midfielder was superb in the engine room all night as the Reds put the Dragons to the sword with an accomplished Champions League performance in Group B.
Jones was at the heart of it all, causing goalkeeper Diogo Costa to spill his shot into the path of Mohamed Salah for the opener before he supplied the No.11 with another assist in the second period.
It was Jones' pass that released substitute Roberto Firmino for the fourth before the Liverpool-born midfielder's shot was deflected into the Brazilian's path for his second and the Reds' fifth late on.
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Klopp revealed that the 20-year-old Jones was a potential absentee prior to the game after receiving a message from the club doctor Jim Moxon.
"Curtis played a good game," Klopp said. "He had some problems before the game with his stomach.
"The doctor came into my room and told me to keep an eye on him, but I told him after the game whatever [the problem] was, keep it!
"He was really good, he was everywhere, involved in everything. He set up the first goal with a surprising finish. The keeper couldn't save it.
"He played, defensively, a top-class game. There were a lot of things I liked a lot tonight, he pressed from the blind side really well.
"So, yes, just keep going Curtis!"
Klopp, whose side meet Manchester City at Anfield on Sunday, added: "Porto had some massive problems today.
"One centre-half was out with a red card in the last game in Chancel Mbemba.
"Pepe couldn't play after getting injured in the warm-up and they didn't have a centre-back partnership that had played together much.
"That doesn't help at all.
"Performance-wise it was good. Porto obviously watched our last game against Brentford because they started direct.
"We sorted it on the pitch step by step."
