Red Bull boss Christian Horner believes Mercedes will be "gone" at the French Grand Prix unless they "screw it up".
Lewis Hamilton and Valtteri Bottas will start first and second on the grid as Formula One returns to France for the first time since 2008.
Sebastian Vettel (Ferrari) qualified third ahead of the two Red Bulls, and their team principal Horner is pessimistic of the chances of catching the Silver Arrows at Circuit Paul Ricard, which is hosting the race for the first time since Alain Prost's 1990 triumph.
"Both drivers have done a great job, fourth and fifth and we can still race well from there," Horner told Sky Sports post-qualifying.
"Mercedes are gone in this race, as long as they don't screw it up they are in a very decent shape, but we are in good shape for a race with Ferrari.
"It is going to be difficult to pass here so it will have to be done on strategy."
RICCIARDO HOPING FOR RAIN
Red Bull's Daniel Ricciardo has won two races this season and needs to start adding to that tally soon to have any chance to stay in contention for the drivers' championship.
But he does not expect to be vying for even a podium, unless the heavens open.
He said: "I would be happy with rain tomorrow. Can I get a podium? With rain, yeah. With a dry race, let's just say we've got more downforce.
"I think I've got more downforce than everyone else, so passing on the straights won't be that easy."
MERCEDES BACK ON TRACK
Mercedes brought an upgraded engine to southern France and the move appears to have paid dividends.
They have not won since Hamilton's triumph at the Spanish Grand Prix, but non-executive chairman Niki Lauda believes they are now back on the right track, though he is wary of the impact of the weather.
"We're back on track. The car was good. Perfect team. Thank God. It was really good," he told Sky Sports.
"We're one race late, but nevertheless, it worked out. Everything in the moment looks right for the race tomorrow. But you know what this place can be like with the weather."
1. Lewis Hamilton (Mercedes)
2. Valtteri Bottas (Mercedes)
3. Sebastian Vettel (Ferrari)
4. Max Verstappen (Red Bull)
5. Daniel Ricciardo (Red Bull)
6. Kimi Raikkonen (Ferrari)
7. Carlos Sainz (Renault)
8. Charles Leclerc (Sauber)
9. Kevin Magnussen (Haas)
10. Romain Grosjean (Haas)
1. Sebastian Vettel (Ferrari) 121
2. Lewis Hamilton (Mercedes) 120
3. Valtteri Bottas (Mercedes) 86
4. Daniel Ricciardo (Red Bull) 84
5. Kimi Raikkonen (Ferrari) 68
1. Mercedes 206
2. Ferrari 189
3. Red Bull 134
4. Renault 56
5. McLaren 40
2008: Felipe Massa
2007: Kimi Raikkonen
2006: Michael Schumacher
Ricciardo's wish for rain may be granted, with thunderstorms, and a 50 per cent chance of precipitation, forecast for the start of Sunday's race.