Despite continuing to press in the second half, led by the efforts of Amad, Liverpool extended their lead with a third goal from left-back Konstantinos Tsimikas at the 61-minute mark.
To add to their woes, United lost substitute Will Fish to injury after he came on at halftime, as he was stretchered off with a protective boot. United's attention now turns to their upcoming match against Manchester City in the Community Shield at Wembley next Saturday.