Lampard was booed when he made his 2016 debut as a substitute in last week's 7-0 Heineken Rivalry Week thrashing at the hands of the New York Red Bulls, though he received a more mixed reception as a 77th-minute replacement for Tommy McNamara on Sunday.
Lampard was one of the club's first signings and expected to play a pivotal role upon his arrival last season. But the England legend has played just 12 games (nine starts, 761 minutes) in his MLS career to date, as a calf injury has hampered his search for match fitness.
The No. 1 selection in January's SuperDraft, Harrison himself has faced somewhat similar struggles in his first season as a professional. A pelvic injury sidelined him for months before he made his debut this month, also against the Red Bulls.