Clifford Chance and Davis Polk & Wardwell took the lead roles in Monday’s biggest deal: Royal Dutch Shell’s decision to dive into Brazil’s sugar-based ethanol market in a $12 billion joint venture with the Brazilian biofuel giant Cosan, according to sources familiar with the deal.

Clifford Chance partner Anthony Oldfield led the team for Shell, according to sources familiar with the deal. Clifford Chance has a long relationship with Shell; the firm has advised the company on several deals around the world, according to our archives and the firm’s Web site. The firm also has had an office in Brazil for more than a decade, which might explain the big day Oldfield is having in Brazilian energy deals. According to a source familiar with the matter, Oldfield advised the Brazilian petrochemical company Braskem on its move to acquire the chemicals wing of Sunoco and the U.S. facilities that come with it. Braskem is paying about $350 million in the deal, according to The Wall Street Journal.