"It's going to be very tough to hold on to Sebastian," McLaren's Button said.
"It's gone his lead. It's also tough for him because Red Bull are so fast. Ferrari are pretty quick but not as quick as Red Bull."
“The most important thing is to stay really rational and not fall into the worst enemy of the team, what the others are trying to put on us, which is pressure”
Stefano Domenicali Ferrari Team Boss
Alonso spun out at the first corner after his left-rear tyre was punctured by the front wing of Kimi Raikkonen's Lotus.
It is the second time in four races that Alonso has been forced into retirement through no fault of his own - he was taken out by Raikkonen's team-mate Romain Grosjean at the start of the
Belgian Grand Prix last month.
The Spaniard said: "It was a shame. It is always sad when you cannot do the first corner but we need to concentrate and think about [the Korean Grand Prix] next week.
"We need to keep working well and not making mistakes. Nothing we can do. Thanks to this consistency we are leading the championship. The others make mistakes, we need to avoid this."
Vettel's victory in Japan meant he drew level with Alonso and McLaren's Lewis Hamilton as the only men to win three races this year.
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