Genoa coach Patrick Vieira had chosen Otoa for the starting-lineup, but the former French international will probably have regretted that decision as the Danish Under-21 international was sent off already after 22 minutes.
Otoa saw red, when he failed to man-mark Mattia Zaccagni properly and pulled the Lazio striker down just in front of the box to prevent him from going face to face with Genoa goalkeeper Nicola Leali.
Genoa is therefore a man down for the rest of the match, with Morten Frendrup in the starting lineup for the home side. Gustav Isaksen is suspended, while Oliver Provstgaard is on the bench for Lazio.
Lazio were leading 1-0 at the interval thanks to a goal after 32 minutes from Taty Castellanos.
The 20-year old Otoa was signed in January from AaB.