The final day of action for the 2025 Challenge of the Americas program at the K1 Circuit was completed on Sunday. Another perfect day of weather at the Winchester, California facility after the two days of rain showers dampening the practice sessions on Thursday and Friday. The massive 1-mile course proved to be a superspeedway for the six categories competing on the new Shinko Kart Racing Tires. The Round Four action on Sunday put the championship chase to the halfway point with the standouts showing well once again, including five drivers doubling up in the win column on the weekend.

With the majority of the Forward Direction Motorsports 100cc Senior field split up randomly for the two qualifying groups, the first half of the 44 driver field went out for qualifying led by Saturday winner Keagan Kaminski (FW / GFC Karting). His 1:05.396 was best over the two groups, however, he was hit with a track limits violation to lose his fast lap. That dropped him down to ninth overall with Nico Sarphati (GFC Karting) earning the pole position for the Prefinal. It took Kaminski only four laps before he returned to the point in the Prefinal, taking the lead from Sarphati to lead a GFC 1-2-3-4 with Chase Hand (GFC Karting) and Johnie Stamps (FW / GFC). The green flag to start the 18-lap Final was the only time anyone was near Kaminski. He jumped out to a solid lead early and never relinquished the spot, driving away to a 2.5-second advantage. The real show in the Prefinal and on the day was Macy Williams (CB / Tony Kart). The ‘Sunday Kid’ repeated her drive from the back to the front that she recorded in Tucson. Starting 44th in the Prefinal, Williams laid down fast laps of the race to move up to 10th. From there, she knifed her way through the pack racing for second. She got to the spot by lap 13 and never let anyone take it away. Williams celebrated her first podium of the season with the runner-up finish and fast lap of the race. Hand was third at the line, but had a track limit violation to put him back to fifth. That promoted Stephen Eisert (SpeedSense / Exprit) up to third step of the podium and Stamps into fourth.

For a fourth straight time, Michael Avansino (RWR / CRG) collected maximum points on the day in the Swedetech Racing Engines Shifter Senior. Avansino put down a 59.629 lap to clear the field by over two tenths of a second. Bryce Stevens (GFC Karting) led for a bit in the Prefinal before falling to third after Avansino broke away late. Stevens jumped up to second at the drop of the green for the Final as Avansino led the way. Throughout the race, Stevens kept close to Avansino, only to suffer a mechanical issue on the final lap, recording the DNF. Avansino went wire-to-wire for a fourth straight victory. Anthony Freese (WCM / Birelart) held off a charging Evan Concepcion (Scuderia Littel / GFC) for the runner-up finish. It was the best performance for Concepcion thus far in 2025. TJ Madonna (GFC Karting) was fourth with Stevens fifth after Nolan Gagnon (Nash / Italkart) retired early.

A perfect four for four thus far on the 2025 season in the Neliton Race Concepts Shifter Masters class for Joe Ruch (Shifterz / Maranello). The Indian driver went wire-to-wire on the day for both the Prefinal and Final. The main event was highlighted by a 12-second advantage over the battle for second. It was Michael Faker (GFC Karting) and Michael Guasch (Shifterz / Maranello) battling once again, this time with Guasch coming up from the back after a Prefinal DNF. In the end, Faker held on for the runner-up spot with Guasch settling for third. Chris Muecke (Italcorse Americas) and Marcin Kloda (Shifterz / Maranello) completed the top five.

The competition level went up one notch on Sunday in the Ruthless Karting 100cc Masters class. Greg Welch (FDM / Pantano) took over the position left by Steve Wiener sitting out Sunday following his flip at the start of the Saturday Final. He was fourth in the session as two-time Tucson winner Scott Falcone (Precision Works / Pantano) earned another fast time in qualifying, working with Matthew Meech (Precision Works / Tony Kart) to go 1-2 ahead of Saturday winner Paul Bonilla (PGR / LN Racing Kart). Falcone led the first three laps until Welch grabbed the spot, showing the way the rest of the distance. Welch and Bonilla fought for the top spot early on, including on lap nine. Bonilla took the lead and former series champion Erik Jackson (Vemme Kart) attempted a move on Welch, making contact. Jackson retired while Welch continued on outside the top five. Bonilla had enough space on the rest of the pack to led the remaining laps for a second straight victory. Christopher Mann (Ruthless / Exprit) was able to secure second in the final corner, crossing ahead of Meech and Damon Duckworth (Speed Factory / Gillard). Falcone was unable to challenge with the group, finishing fifth.

The Nash Motorsportz 100cc Junior class welcomed another new winner. Junior rookie Daniel Ramirez (Team KartNick / Tony Kart) put in the fast lap in qualifying, a 1:05.297 lap to edge out Round One winner Erik Doan (Nash / EOS) and Luca Popescu (GFC Karting). Two-time winner Jackson Gibson (NRC / Gillard) join in the mix, however, it was Doan taking the win in the Prefinal over Ramirez. The two went back and forth for the lead before Gibson worked himself to the point in the early laps of the Final. Eventually Doan and Gibson swapped the top spot multiple times with Ramirez right there as well. In the closing laps, with Ramirez leading, the lead group became over seven drivers. On the final circuit, two incidents occurred. In turn eight, Doan was caught up in contact. The following corner, more contact sent Cole Anderson (GFC Karting) and Matthew Cagle (FW / GFC) into the tire barriers. Thankfully, every driver was able to walk away. Up front, Ramirez was able to go unchallenged to the checkered flag for his first series victory, winning by over three seconds. Brayden Wagner (FW / GFC) was able to get up to second ahead of Gibson and Xander Malatesta (Ruthless / Tony Kart). Both Gibson and Malatesta had a track limit violation, dropping them to fourth and fifth, promoting Payton Anderson (Nash / LN Racing Kart) to her first career Challenge podium.

Only 81 thousandths separated the top five drivers in The Karting Collective 60cc Cadet division. Brandon Ng (SG / Parolin) came out of the session with fast lap, a 1:10.842 time. It was Lucas Tarango (Ruthless / Nitro Kart) jumping out to the lead in the Prefinal, battling with Nathan Ramirez (Team KartNick / Parolin) for the lead. In the end, it was Hudson Hidalgo (Parolin) coming through on the final lap for the win. Hidalgo fell back to second at the start of the Final with Ng taking the point. Two-time winner Luis Martinez (Croc Promotion) was third, jumping to the lead on lap six. From there, Martinez was able to keep the top spot for the remaining nine laps to earn a third straight victory. Ng was second on the final lap, pushed back to fifth as Andrew Janus (HRT / Kosmic) worked up to second ahead of Arran Speirs (Nash / Italkart) and Hidalgo. Speirs had three track limit violations, thus, dropping him back to eighth, promoting Hidalgo to third, Ng to fourth and Tarango in fifth.

The Challenge of the Americas is slated to return to action, kicking off the second half of the season with a return to the Sonoma Raceway facility in northern California on the April 25-27 weekend.