Portimão began with the GT3 championship tied, BS+COMPETITION and Grid-and-Go.com eSports level on 56 points after COTA. Bleu Mercure Esport led PCUP by 8. Team75 Bernhard by SimRC, winners of all 3 GT4 rounds so far, led Byte.Collino Max by the same margin. Jarno Koch put the Grid-and-Go #1 on pole by 0.06s from Ryan van de Grijp's Maniti Racing Green Ferrari and James Beumee's Falken, but grid order mattered less than the rulebook. The split-service rule bans refuelling and a tyre change in the same stop, and the 75% fuel cap forced a stop roughly every 45 minutes. In 38C air, on a track that would peak at 48.9C, every crew had to decide 7 times over how much rubber it could skip.

The first crack came at T+14m. Threading GT3 traffic through Turn 6, Adam Isaksson's Team75 Cayman and the Byte.Collino Pro car touched and both slid into the gravel as the faster cars streamed past on either side. Race control showed the championship leaders the meatball flag¹, the repair took nearly 17 minutes, and the car was 9 laps down inside the first hour. It got worse. At T+3h40m a chat message from co-driver Gareth Higgins confirmed the crew had also forgotten to fuel the car: "At least this happens when we're already 9 laps down and not leading a race." Three wins from three, and now an afternoon of circulating for scraps.

The GT3 window opened at T+46m and the front group came in together. Koch took 4 tyres. Beumee took none, "a bold bold call" in the booth's words, and cycled out leading. Van de Grijp took 2 and popped out ahead of the pole car. GT4 split the same three ways: CoRe SimRacing and Fiercely Forward skipped tyres and went 1-2, Team Checkmate fell from first to third on a full set, and Byte.Collino Max dropped from second to seventh.

The verdict took about 15 minutes. Koch, in clear air on fresh rubber, took 1.1s to 1.5s a lap out of Beumee and started eating into a 16s gap. CoRe's no-tyre gamble fell from the GT4 lead to seventh in the space of 3 minutes: no grip, no balance, then a spin at Turn 3. Maniti's 2-tyre middle path, left sides only at every other stop, looked like the pick of the bunch.

The next pit stop is where everyone kind of has to show their hands and the bluff ends.

— Booth call, T+1h14m

Then, at T+1h19m, the experiment lost its subject. Beumee dropped from the server while leading GT3. Falken got the car back out well down the order and the no-tyre run was never judged on its merits. "True crime podcasts will be made about that disappearance." The car recovered to fourth. The booth reckoned it could have been fighting for the win.

The moment that reshaped the GT3 championship came at the second stops. Race control black-flagged BS+COMPETITION's #89 for speeding on pit exit at T+1h35m, moments after its first driver change. The booth suspected the swap had reset the pit limiter. Running fourth at the time, the car served a stop-and-hold of roughly 40s in its box, plus two 5s penalties it already owed, and spent over 1m20s in the lane in total, "the best part of a whole lap". It rejoined outside the overall top 20.

Catastrophic right now for the 89.

— Booth call, with the #89 stationary in its box

The tally by the flag was 13th in class, a lap down, with a 15s contact penalty on top. From level on points to 3 points scored. Up front the poker game settled into patterns. Grid-and-Go took 4 tyres at every one of their 7 stops, Koch and Sven Haase alternated stints, and the #1 led 177 of the 205 laps. Maniti held second on their every-other-stop rhythm, with SZESE E-Sport's 2-tyre calls keeping Dániel Oláh within reach of both. Maniti's one attempt at more, a no-tyre stop at T+3h57m that closed van de Grijp to 7s of Koch, was 22s back again by T+4h20m and losing a second a lap. "This is a big risk for Maniti to try and get closer to Grid-and-Go, but I'm afraid it hasn't really worked."

PCUP never settled. The lead had already changed hands twice when pole-sitter Gunonso Tasdelen bounced the Grid-and-Go #901 off the final-corner kerb at T+2h42m and spun as a GT3 went around the outside. The stops that followed left Rafał Szołtysek's Impulse Racing car, Maxence Godiinho's Bleu Mercure and Hady-Noah Mimassi, now in the #901, covered by under a second. Mimassi passed Godiinho, then at T+2h56m launched a dive to the inside at Turn 3 that shoved Szołtysek wide and took the lead. "It was ambitious, it certainly was, he somehow made it work."

Szołtysek took it back at T+3h38m, up the inside after a Mimassi bobble out of Turn 13, and Mimassi cut across him on the way into pit entry. Tasdelen, back in the #901 for the next stint, led again. Szołtysek closed through the GT4 traffic at the end of every stint, and by T+4h26m the gap was half a second. Rather than take it to the flag, Grid-and-Go pitted early at T+4h30m and put Mimassi back in for the final 90 minutes.

Tasdelen's in early! He doesn't want this fight!

— Booth call, T+4h30m

The early stop did not win the fight. It handed it to someone else. Bleu Mercure had pitted early too, and at T+4h47m Godiinho emerged leading the class by 2.3s from Mimassi with Pascal Costa's Impulse car 4.7s further back. Then Mimassi lost a chunk of time in contact with a BMW at the pit exit around lap 180, the #901 fell to third, and with 40 minutes left Bleu Mercure led Impulse by 10s.

GT4 had come down to two cars. Pole-sitter Konrad Zerebiec built the early gap for Team Checkmate Wolak Group, but a 2-tyre call around lap 124 started giving it back, and by the time Milosz Smuk took over the #488 at T+4h Byte.Collino Max were 15s behind, then 6. When Smuk finally stopped, Ivan Llenderoso rejoined under 3s behind, and at T+4h51m the pair went through Turns 1 to 5 side by side while GT3 traffic split them, a Myrmica Ferrari putting 2 wheels on the grass between them. Llenderoso came out ahead and by T+5h20m was 2s clear. "I think the 444 is favorite right now, and I'm not sure that Smuk really has an answer."

Then everyone stopped for the last time and the order flipped. Llenderoso pitted at T+5h24m for fuel and tyres and sat 57 seconds stationary. Smuk came in 5 minutes later. Anything under 40s would keep the lead. His stop was 16s shorter than Llenderoso's and the #488 emerged "way, way out in front". GT3 turned over in the same 3 minutes: van de Grijp's 20s stop locked in second, and Oláh's 21s stop lifted him to third, 9s ahead of the Falken, which had taken tyres and paid for it.

It's amazing how much things are changing at the very end. It's what we wanted with the introduction of this split in pit strategy calls.

— Booth call, T+5h31m

PCUP still had one stop to come, and it belonged to Costa. Godiinho had taken tyres at T+5h24m in a 36.8s stop and then found himself behind a yet-to-pit Altitude FreeM Cup car, losing 0.5s, then 0.6s, a lap. Costa had stayed out on the extra fuel. With 15 minutes left he came in for a 12.8s splash, 24s shorter than Bleu Mercure's stop, and rejoined roughly 13s clear. "I think Pascal Costa and Impulse Racing have pulled a strategic masterclass here." Impulse won by 10.7s. Costa called it "wild", and credited Szołtysek, who "was flying" while saving tyres.

Haase crossed the line 35.5s clear of van de Grijp with Oláh third, Grid-and-Go's second win of the season. Koch called it "a flawless race". "For us we don't really look into the championship, for us we want to win every single race we drive." Smuk held on in GT4 by 2.9s from Llenderoso, who cut the gap from 8s in the final 15 minutes and ran out of laps. A first win of the season for Team Checkmate Wolak Group, a third straight second place for Byte.Collino Max, 13th for Team75.

I'm not the fastest in the team... The track isn't made for me, so I needed to do as much as I can to stay in that first position.

— Milosz Smuk, GT4 winner

The table now applies the drop score², and it keeps the day's two biggest losers alive. Grid-and-Go.com eSports lead GT3 on 58 to BS+COMPETITION's 56, the #89's Portimão score already discarded. Bleu Mercure hold PCUP on 56 from Grid-and-Go and Impulse Racing, both on 52. Team75 Bernhard by SimRC still lead GT4 on 60, their 3 points dropped, from Byte.Collino Max on 54 and Team Checkmate Wolak Group on 46. The booth said on air that Byte.Collino Max had taken the GT4 lead. On raw totals they have, 70 to 63. On the table that counts, they have not. Round 5 is the series' first street circuit, Adelaide, on 4 October, and the 12-hour Silverstone finale that follows cannot be dropped.