Team Penske's Will Power topped second practice at Portland International Raceway ahead of this weekend's Portland Grand Prix, improving his standing of fifth fastest from the first session of the weekend.
Practice at Portland was broken up by a series of red flags, with Rahal Letterman Lanigan Racing's Takuma Sato and former series champion Simon Pagenaud both taking trips into the barrier.
Power's best lap of the session, a 57.4053s tour of the 3.13km-long circuit, beat Marco Andretti to the top spot on the timesheets by a slim margin of 0.0615s, with the driver of the #98 machine heading rookie Santino Ferrucci who set the third fastest time for Dale Coyne Racing.
Championship leader Scott Dixon slipped down by two positions to set the fourth fastest time of the session, 0.1609s adrift of Power while Britain's Jack Harvey completed the top five.
Reigning IndyCar champion Josef Newgarden was sixth fastest in the #1 Team Penske Honda while Gabby Chaves trailed the 27-year-old by only 0.0068s in seventh fastest.
Zach Veach ended the session with the eighth fastest time, 0.0003s adrift of Chaves in seventh while Jordan King put in a commendable performance to finish the session in ninth for Ed Carpenter Racing.
Sebastien Bourdais, who topped first practice at Portland, completed the top 10 and was followed by Spencer Pigot, James Hinchcliffe, Pagenaud, Charlie Kimball and Ed Jones who completed the top 15.
Robert Wickens' replacement of the weekend, Carlos Munoz, set the 16th fastest time and trailed Jones by 0.0127s.
Ryan Hunter-Reay only managed 17th in the session while he was followed by Carlin's Max Chilton in 18th.
Pietro Fittipaldi turned his first laps of the day in FP2 after recovering from a braking problem in first practice to set the 19th fastest time while he was followed by the Rahal Letterman Lanigan Racing pair of Graham Rahal and Sato in 20th and 21st.
Tony Kanaan, Alexander Rossi, Matheus Leist and Alfonso Celis Jr rounded out the timesheets.
