The first qualifying session at the Macau Grand Prix today has been postponed until tomorrow after Portuguese rider Luis Carreira was involved in an accident.
The red flags were deployed after 10 minutes of the session and further details of the seriousness of the incident are unknown.
Event specialist Michael Rutter had been leading the times by 1.6s on his SMT Honda from Martin Jessopp (Riders Ducati), John McGuinness (SMT Honda) and Gary Johnson (Quattro Plant Honda).
Rutter is chasing a record eighth victory at Macau.
Earlier, Isle of Man TT star McGuinness topped the first free practice session for the 46th running of the famous race on the SMT Honda Fireblade.
McGuinness set his fastest lap in a time of 2m 29.914s to head the times by 0.768s from Jessopp on the Riders Ducati.
Jessopp finished second behind Rutter in 2011 and is among the chief protagonists for Saturday's race.
Rutter was third fastest on the second SMT Honda followed by Austrian rider Horst Saiger (Kawasaki), who was more than three and a half seconds off McGuinness' quickest lap.
Roads race star McGuinness said: “It was hot, muggy, sweaty out there! I've been here many times but I was quite nervous before the start of it.
“It was good. I hit all the apexes and tried to be nice and smooth and not scare myself.
“I'm quite surprised to be P1 to be honest. I'm happy with that,” he added.
“So we'll keep building on that and see what qualifying brings.”
Lincolnshire rider Johnson and Carreira were fifth and sixth fastest respectively, followed by James Hillier on the Bournemouth Kawasaki and Simon Andrews (Ice Valley BMW).
Manx rider Conor Cummins was ninth on the Tyco Suzuki ahead of Jimmy Storrar.
Northern Irish newcomers Lee Johnston (RPM Performance Ducati) and Jamie Hamilton (RPM Performance Kawasaki) were 20th and 24th respectively as they sampled the infamous Guia street circuit for the first time.
Ex-British Superstock 600 champion Johnston quickly made his mark as he ended the opening free practice session as the fastest newcomer after the hour-long session.
Final qualifying is scheduled to take place tomorrow.