Manx riders Ryan and Daniel Kneen became the first brothers to win Manx Grand Prix Newcomer races in the same year.
Ryan took the chequered flag in the "A" class with elder brother Daniel taking the "C" class honours.
Racing finally got underway around the Mountain Course six and a quarter hours later than scheduled after rain and low cloud delayed the action.
The Newcomer race was reduced to half distance over two laps.
In the Senior Classic, Ryan Farquhar won on the Paton for the second year in a row.
He finished just over twenty seconds ahead of Alan Oversby who recorded only his second classic race finish in twenty years.
And there was more cause for Manx celebration when Ramsey's Allan Brew completed the podium places in third.
Racing continues on Wednesday.
Athletics: Island trio impresses on world race walking stage
Sidecars excluded from Southern 100
Football: Draw made for 2026 Paul Henry Gold Cup
Jamie Coward happy with progress so far on TT return
Franco Bourne planning TT return after missing debut