The Reds lost 4-1, with Phillips played at the back.
The centre-back has yet to kick a ball under Jurgen Klopp this season despite signing a new contract in the summer.
And Academy coach Barry Lewtas was impressed with the manner in which Phillips embraced the opportunity of minutes.
"The first-team staff spoke to us and said Nat was keen to play," says Lewtas. "The group is here for that as well, to give lads minutes.
"We have had a massive amount of games as a lot of our lads played in the UEFA Youth League as well, so it was a chance to give Billy Koumetio a bit of a breather.
"When did I last coach Nat? It may have been under-14s at Bolton, so it was like the old days!
"He is a fantastic young man and for him to come in, and train with us properly for the last few days, it's great to have him around."
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