Manchester United boss Louis van Gaal said Anthony Martial's debut goal in their 3-1 win over Liverpool came after impressing in his first few days.
Martial, 19, was signed for £36m from Monaco, making him the world's most expensive teenage footballer, and was named as a substitute at Old Trafford.
Van Gaal said: "He made a very good impression in the first three days, that's why I selected him on the bench.
"When you make a goal like Anthony you cannot wish for more."
Martial's 86th-minute goal in Saturday's win came two minutes after Christian Benteke had pulled a goal back for Liverpool with a spectacular bicycle kick.
The teenage substitute jinked past defend Martin Skrtel before slotting into the far corner at the Stretford End, sending Old Trafford wild.
Van Gaal had previously admitted that the pressure to succeed was higher at Manchester United than at other clubs, citing the likes of Angel Di Maria and Radamel Falcao, who were signed last season.
But despite the debut goal, the Dutchman said it was too early to judge whether Martial could live up to the hype.
"A lot of players have made a debut and scored with me so it's a good signal," Van Gaal.
"We scouted him and we wanted him because he's the best in his age, but he needs time and three days is too short to judge his personality."
Rooney doubtful for Champions League tie
The victory came after rumours of dressing room unrest, with skipper Wayne Rooney and Michael Carrick telling the Dutch boss that the atmosphere amongst the squad was flat.
Rooney was absent with a hamstring injury, with Van Gaal saying that the England captain - who broke the England scoring record against Switzerland last week - could be a doubt for Tuesday's Champions League trip to Dutch side PSV Eindhoven.
Van Gaal added: "I don't think he should play on Tuesday, we don't want to take any risks with our captain but you never know. It's Saturday and we still have Sunday and Monday."
The Manchester United boss also said he took off Memphis Depay for "tactical reasons". The former PSV forward, who signed for £31m in June, was replaced at half-time by Ashley Young.
"In the third and fourth phase, he could have played the last pass better," said Van Gaal.
Van Gaal pleased after 'difficult transfer window'
United's win - their third of the campaign - moved them up to second in the table, five points behind leaders Manchester City.
And the 64-year-old said he was pleased with his team's start after a a tricky time in the transfer market, which featured David De Gea signing a new four-year deal after his protracted move to Real Madrid broke down and the signing of Martial on deadline day.
"It was a difficult period in the transfer period with a lot of problems with players who are going and coming," said the United boss.
"I think we have managed that very well. We have 10 points from five matches. That is a good record, there is only one club better and our aim is to be the best but now we are five points behind Manchester City. We still look to that position but I am happy."