EDMONTON, Alberta -- The complexion of the starting grid for the Edmonton Indy changed since qualifications less than 24 hours earlier as three of the four top contenders for the IZOD IndyCar Series championship were assessed engine change-related 10-grid spot penalties.

Pole winner Ryan Hunter-Reay and Will Power -- 1-2 in the standings -- were assessed 10-grid spot penalties because of unapproved engine changes.

The Chevrolet engine in the No. 28 Team DHL/Dr Pepper car driven by Hunter-Reay was swapped out following his victory on the streets of Toronto two weeks ago before it reached its mileage limit. Andretti Autosport said it was precautionary as the car of teammate James Hinchcliffe developed an engine issue in practice. He'll start 11th.

Click it: Starting lineup | Warm-up results | Combined practice results

Power, who won the Edmonton Indy in 2011 and '09, enters the 75-lap race on the 2.224-mile, 13-turn City Centre Airport circuit 35 points behind the front-running Hunter-Reay in the standings. The Chevrolet engine in the No. 12 Verizon Team Penske car was changed after he qualified seventh and he'll start 17th.

Scott Dixon, who qualified eighth in the No. 9 Target Chip Ganassi Racing car and is fourth in the standings, was levied a 10-grid spot penalty because the entry is using its sixth Honda engine. According to the engine manufacturer agreement for 2012, five fresh engines are allowed for the season.

Dixon was quickest in the 30-minute morning warm-up session with a lap of 1 minute, 16.9006 seconds. Rubens Barrichello was second (1:167.4653) in the No. 8 BMC-Embrase-KV Racing Technology car. Mike Conway, who had a fuel pump issue in qualifying, was third quick in the No. 14 ABC Supply car for A.J. Foyt Racing.

Dixon, celebrating his 32nd birthday, won the 2007 race at Mid-Ohio Sports Car Course on his birthday.

Power's Team Penske teammate, Helio Castroneves, who is third in the standings with five races remaining, qualified sixth and will share Row 3 with rookie Simon Pagenaud in the No. 77 Schmidt Hamilton HP Motorsports car.

Also receiving grid penalties were Panther/Dreyer & Reinbold Racing's Oriol Servia, who qualified 20th. The team changed the Chevrolet engine following qualifications. Simona de Silvestro, who qualified 23rd in the No. 78 Nuclear Clean Air Energy car for Lotus HVM Racing, received a penalty for surpassing the five-engine limit.

The Chevrolet engines in the No. 4 National Guard Panther Racing car driven by JR Hildebrand and the No. 26 Team Dr Pepper car driven by Marco Andretti were changed out following qualifications/warm-up as they reached their 1,850-mile ceiling.