Watford defender Ben Wilmot made his debut for loan club Udinese in Friday's defeat to Juventus.
The England Under-20 international's first appearance was to be curtailed at half-time, with Juventus already two goals to the good through a Moise Kean brace.
An Emre Can penalty and Blaise Matuidi header made it 4-0 to the hosts after the break before the player who replaced Wilmot, Kevin Lasagna, netted a consolation.
Fellow Hornets loanees Marvin Zeegelaar played the full 90 minutes while Stefano Oakaka was unused substitute.