WATKINS GLEN, N.Y. — Indianapolis 500 champion Alexander Rossi will return to Andretti Autosport for the 2018 IndyCar Series season.

The multiyear agreement was announced Friday.

Rossi has a 10-race sponsorship with Napa Auto Parts for his third season in the open-wheel series. That partnership began in May 2016 before Rossi's breakthrough victory in the 100th running of the Indy 500.

Rossi declined to elaborate on the length of the contract after opening practice Friday at Watkins Glen International.

Rossi is seventh in points with two races left in the season. He is the third driver confirmed to drive for Andretti next year. He joins teammates Ryan Hunter-Reay and Marco Andretti. That leaves Takuma Sato, this year's Indianapolis 500 winner, as the lone Andretti driver to announce plans for next year.

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