Mason Greenwood's second-half goal made the difference for Manchester United as they edged out FC Astana in the Europa League.
The 17-year-old netted on 73 minutes with his first senior goal to secure a 1-0 win.
Ole Gunnar Solskjaer named a starting line-up with five academy graduates, including Greenwood, Tahith Chong and Angel Gomes.
But the home side could only muster one goal in their Europa League opener.
Elsewhere in United's group, AZ Alkmaar drew 2-2 at Partizan Belgrade.
Earlier in the night, Arsenal got their campaign off to a good start. Unai Emery's side triumphed 3-0 at Eintracht Frankfurt.
Joe Willock, Bukayo Saka and Pierre-Emerick Aubameyang got Arsenal's goals on the night.
Frankfurt had Dominik Kohr sent off before the Gunners' last two goals.
Arsenal go top of the group above Standard Liege who beat Vitória Guimarães 2-0 in Belgium.
Meanwhile, Celtic drew 1-1 at French Cup winners Rennes, with Ryan Christie's penalty earning the Hoops a point.
Five-time Europa League/UEFA Cup winners Sevilla won 3-0 at FK Qarabag, while AS Roma thrashed Istanbul Basaksehir 4-0 at the Olimpico.
Steven Gerrard's Rangers won 1-0 at home to Jaap Stam's Feyenoord. Wolverhampton Wanderers however lost 1-0 at home to Sporting Braga.