Reigning IndyCar champion Josef Newgarden expects Andretti's Alexander Rossi and surprise standout Robert Wickens to feature in the 2018 title fight.
Newgarden took his first victory of the year at Phoenix following a "risky" late pass on Wickens, and now leads the drivers' standings by seven points over Rossi after two races.
Rossi recovered from an early drivethrough penalty that dropped him to the back of the field to finish third and keep in touching distance of Newgarden in the standings.
While Wickens is currently down in eighth in the championship after losing a sizable amount of points after a collision with Rossi while leading the St Petersburg season opener, Newgarden believes he will still join the title fight.
"I think both Rossi and Wickens will be strong all year," said the Newgarden.
"Honestly, I'd be surprised if you don't get a lot of yo-yo-ing between the whole field this year.
"[It] seems like this with new car, until everybody figures it out, there's going to be a lot of back and forth with the grid.
"People will make mistakes, people will mess up in qualifying. I think you're going to see a very mixed-up grid more times than not this year.
"But Rossi, and Robert specifically, yeah, I think they're going to be in the battle. They're both very good.
"I'd be surprised if they don't keep up their pace like they have at the beginning of the year."
Penske and Newgarden were initially caught out halfway through the Phoneix race when Schmidt Peterson Motorsports performed an undercut that cycled James Hinchcliffe and Wickens into first and second.
Wickens dispatched his team-mate and led the later stages, but Newgarden's late stop under caution for new tyres gave him the advantage he needed to win.
When asked how highly he rated Wickens's transition to IndyCar, Newgarden said: "He's a stud.
"He's not new to motorsports. Robert has been one of the best drivers in the world for many years, I think.
"He probably should have been in IndyCar a lot sooner than this, people will argue that.
"He's a North American guy. One of the best out of Canada that we've had over the last 10 years, in my opinion. It's good to have him in the series, he deserves to be here.
"I think he's already proved his worth driving in IndyCar. He's come at a great time, it's a new car. It's been very challenging, and rookies seem to be shining. Robert is very capable.
"He drove really well [in Phoenix]. He gave me a lot of racing room, raced me hard. Hopefully, we have some more battles.
"I have a feeling we're going to have some more battles this year, and I look forward to that."