Jorge Lorenzo won his fourth straight race in a Yamaha one-two finish with Valentino Rossi at the Catalonia Moto Grand Prix, tightening the championship fight between the teammates.
The two-time former champion's 37th career MotoGP victory left him one point behind Rossi at 138-137 in the championship standings.
1. Valentino Rossi (Yamaha) - 138
2. Jorge Lorenzo (Yamaha) - 137
3. Andrea Iannone (Ducati) - 94
4. Andrea Dovizioso (Ducati) - 83
5. Marc Marquez (Honda) - 69
Marc Marquez saw his bid to defend his title take another blow when he crashed out for a second straight race while trying to overtake Lorenzo.
Lorenzo had a great start from third on the grid and never gave Rossi an opening after going past pole sitter Aleix Espargaro and Suzuki partner Maverick Vinales.
He then negotiated the 25 laps of the 4.7km Barcelona-Catalunya Circuit to win in 42 minutes, 53.208 seconds.
Rossi crossed less than a second later, followed by Honda's Dani Pedrosa in third, almost 20 seconds off the pace.
"Valentino pushed me so hard, but at the end the effort was worth it," said Lorenzo, whose winning run includes the Spain, France and Italy MotoGPs.
After starting from fourth on the grid, Marquez had moved up into second by the third lap when he lost control of his Honda trying to overtake Lorenzo on the outside and ended on his side in the gravel.
He also failed to finish the last race in Italy and in Argentina.
With 69 points, Marquez's hopes for a third straight title are fading with 11 races left.