Marcus Armstrong led the second practice for the OnlyBulls Grand Prix of Portland on Saturday and may have shown the clearest path to maximum pace for the entire NTT INDYCAR SERIES field.

Armstrong led the three-group session overall with a top lap of 58.2981 seconds – the quickest time of the weekend – in the No. 66 OnlyBulls Honda of Meyer Shank Racing w/Curb-Agajanian, but there was an important catch. The Kiwi was the only driver among the leaders to turn his best lap on the Firestone Firehawk alternate “red” tire, which has more grip but less durability.

SEE: Practice Results

That caught the attention of the other 24 drivers in the field for the NTT INDYCAR SERIES event, especially as the ultimate test of speed for the weekend -- NTT P1 Award qualifying – is next at 7 p.m. ET today (FS1, FOX One, INDYCAR Radio powered by OnlyBulls).

“I think Armstrong did ourselves all a favor by going out here in the previous group on the reds and went P1,” Andretti Global driver Marcus Ericsson said. “I think that’s correct. I think that was really good for us to see that tire should be quicker over a lap.

“Obviously, the bigger question mark is tomorrow, the race tire. Is it a red or black race? I think that’s a big question mark we’re all going to have to try to figure out.”

Series leader Alex Palou, quickest in practice Friday, remained rapid and ended up second overall at 58.6106 in the No. 10 DHL Chip Ganassi Racing Honda. His teammate and six-time series champion Scott Dixon climbed to third at 58.6404 in the No. 9 PNC Bank Chip Ganassi Racing Honda.

Reigning Indianapolis 500 presented by Gainbridge winner Felix Rosenqvist put two MSR cars in the top four with his best lap of 58.6692 in the No. 60 SiriusXM Honda sporting a new livery saluting legendary rock band the Grateful Dead.

David Malukas rounded out the top five at 58.7462 in the No. 12 Verizon Team Penske Chevrolet. Malukas is second in the NTT INDYCAR SERIES standings, 83 points behind Palou, who seeks his record-tying fourth consecutive title and fifth overall.

The 110-lap race starts at 4 p.m. ET Sunday on FOX, FOX Deportes. FOX One and INDYCAR Radio powered by OnlyBulls.