Yamaha MotoGP rider Valentino Rossi suggests that the top speed advantage enjoyed by rival squad Ducati could be "a problem for everyone" in the Qatar race.
Ducati factory riders Andrea Iannone and Andrea Dovizioso were first and second in the top speed charts in first free practice - and were the only two riders to break the 340km/h barrier as Iannone clocked in at 347 km/h (216mph).
And Rossi, who finished second to teammate Jorge Lorenzo in laptimes and whose top speed of 338km/h (210mph) was best among the Yamahas, appears to be concerned about the Italian marque's advantage on the straights.
"It looks like Ducati is a problem for everyone," Rossi said, "because the GP16 has 8km/h more [on the straights than the Yamaha YZR-M1].
"It's a problem because, if they can stay behind, they overtake on the straights."
Losail International Circuit's main straight is over a kilometre long, with the finish line located a long way from the final turn.
As such, Rossi's concerns over Ducati's top speed were echoed by teammate Lorenzo, who said: "If they can stay on the pace, and there is a Ducati behind, it will be very difficult to keep the position on the straight. We hope to be some metres ahead."
However, Rossi remains confident about the advantages the Yamaha bike enjoys over the Ducati in other areas.
He added: "Our bike is still better in the corners, better on the tyres. But we just talk - nobody knows until Sunday night."
Additional reporting by Oriol Puigdemont