Bruno Senna has been ruled out of next weekend’s Mobil 1 Twelve Hours of Sebring with United Autosports, leaving an open seast in the team’s Ligier JS P217 Gibson for the second round of the IMSA WeatherTech SportsCar Championship season.

The Brazilian, who missed last month’s IMSA-sanctioned test at the Florida airfield circuit, has elected not to compete in the race after undergoing a surgical procedure in Sao Paulo in “recent weeks.”

While skipping the Sebring race has come at the recommendation of his doctor, he was present at the launch of the Rebellion R13 at the Geneva Motor Show on Tuesday and is expected to complete a seat fitting in the LMP1 car later this week.

Alex Brundle joined Phil Hanson and Paul di Resta at the Sebring test last week and is believed to be among the favorites to fill in for Senna in the race.

The Anglo-American squad campaigned two cars in the season-opening Rolex 24 at Daytona, with Hanson joined by Lando Norris and Fernando Alonso.