The teenage winger was a regular in the Reds' starting line-up at the start of the season, when his form brought a full England cap against Sweden.
But Brendan Rodgers' has started Sterling just twice in the Premier League in 2013, and England U21s benefited on Thursday as the well-rested 18-year-old starred in the friendly win against Romania.
Coach Brian Eastick said: "He was very good. Brendan has obviously rested him a little bit recently.
"He hasn't played a great deal of football of late so getting a game under his belt with benefit him. He is a talented player and I think possibly that rest has helped.
"Brendan felt he had to take him out of the firing line a little bit at Liverpool. He is a very young player and people forget how young he is. You do need to rest players at the right time.
"Possibly it has done him a little bit of good and he enjoyed his game against Romania. His performance was very good."