Britain's Kat Matthews put a calf tear and 5min drafting penalty behind her to defend her Ironman Texas title and clinch qualification for this year's Ironman World Championship in Nice.
Having pulled up with the injury in Miami T100 last month, there was a question mark over whether the army physiotherapist would be fit to start in the North American Championships, the second stop on this year's Ironman Pro Series.
It took until halfway through the marathon in The Woodlands before the 33-year-old gained the lead and then nursed her advantage to the finish line despite appearing struggling through the closing miles due to the calf.
In the men's race, there was a career breakthrough performance for Mexican youngster Tomas Rodriguez Hernandez, who in his first full distance swim-bike-run clocked a scorching 2:34:14 marathon to see off two-time Hawaii champion Patrick Lange, the German moving to the top of the Ironman Pro Series standings as consolation.
There wasn't such good news for the rest of the competing British contingent. After fighting his way back into the race on the bike, Joe Skipper pulled out on the run.
Longtime leader in the women's race Fenella Langridge also suffered in the heat and slipped back through the field on the marathon to finish sixth.
In high humidity, Simone Mitchell DNFd early on the bike, as did John Thelwell. Will Crudgington also dropped out on the run, while Finn Arentz finished 21st, Tom Davis (27th), Andrew Horsfall-Turner (32nd), Liam Lloyd (39th).
Men's race
What happened in the swim?
With temperatures up to 24 degrees, it was a non-wetsuit swim in the man-made waterways of The Woodlands, a settlement north of Houston, which helped separate the field.
Last year's leader out of the water Horsfall-Turner was 31sec back in seventh place, underlining the race had been taken out hard.
The Netherlands Menno Koolhaas was first into T1 in 48:04, closely followed by Germany's Florian Angert, with pre-race favourite Lange and Braden Currie about 1min down with Rodriguez Hernandez. Skipper was 41st out of the water, more than 8min down.
What happened on the bike?
It was last year's third place finisher Marquardt and Sweden's Robert Kallin who drove the pace on the bike as they headed out for two laps on the fast highway of the Hardy Toll Road.
The pair opened a sizeable gap over the field, among them France's reigning World Triathlon long course champion Clement Mignon before Kallin took a tumble in the final miles when he looked to slip on a pedal stroke.
It left Marquardt clear to enter T2 on his own after an impressive 4:03:22 bike split.
Rodriguez Hernandez came off the bike in fifth place 12in 45sec adrift. Lange was more than 13min down, while Skipper laid down one of the day's best splits (4:10:22) to dismount alongside fellow Brit Liam Lloyd and round out the top 10.
What happened on the run?
While Marquardt and Kallin had a huge gap starting the run, Rodriguez Hernandez covered the first half of the marathon in under 74mins, reeling in the leaders and opening up a 4min gap on Lange.
Marquardt was showing signs of struggling when he stopped to embrace his family and Rodriguez Hernandez took the lead shortly afterwards.
Mignon was running consistently for an eventual third place, but while Lange started to close fast within the closing few miles, Rodriguez Hernandez had done enough damage to take the tape in 7:42:38 and become the first Mexican to win a professional Ironman race.
Patrick Lange quotes:
"I love the people in Texas and it's a great place for me. It's where I took my first Ironman victory in 2016 and it's my first time racing here since.
"I had a rough day and so I'm really happy with the outcome. I had an OK swim but was struggling because the bike was windy and as a lighter athlete it's hard to push big watts on a flat course.
"The run is my joker. I think it's cool for the fans. They know that when I'm in the race it's not over until the finish line.
"I had the foot power to run myself into a great position again and I'm happy that it almost worked out."
Tomas Rodriguez Hernandez quotes:
"I don't have any expectations, I want to win. The bike I wanted to survive and I wanted to run first two laps so fast and the last lap I wanted to survive.
"It's not much heat [for me]. I recently raced in Campeche in 40 degrees and this is very comfortable for me. Racing in Texas is like racing in Mexico. It's a second home.
"I want to run more fast and in the future think i could run like 2:28. I also want to win the Pro Series. I had a very bad race in Oceanside [finishing 45th], but this was an incredible race for me."
Ironman Texas: Men's results
- Tomas Rodriguez Hernandez
- Patrick Lange
- Clement Mignon
- Matt Marquardt
- Robert Kallin
Women's race
What happened in the swim?
Renowned US swimmer Lauren Brandon led out the swim in 51:46, followed by four women including Lotte Wilms and Fenella Langridge.
Matthews was just over 4min down, with third Brit Simone Mitchell almost 13min down, but with her best disciplines to come.
What happened on the bike?
Wilms, Langridge, Brandon and New Zealand's broke clear at the start of the bike, but the early drama came in the forms of 5min drafting penalties for Matthews and Denmark's Stage Nielsen.
Langridge and Wilms were first into T2 after the 112 miles, with the Brit looking the fresher as she headed out on to the marathon.
Behind them there were another five women within 7mins, including Matthews, who hadn't been fazed by the penalty and despite the enforced break rode just 2min slower than Australian Penny Slater's race-best 4:39:39 split.
What happened on the run?
Langridge led through the first 10 miles, but Matthews was slicing chunks off the lead from the get-go. Wilms briefly took charge before Matthews moved into the lead.
Slater was producing a well-judged race to move into second place around 19 miles, but although Matthews was walking through the aid stations to take time cooling and getting nutrition, she retained control to take the tape in 8:42:22.
Kat Matthews quotes:
"It was good enough and I'm proud of the whole experience.
"I had a great swim start but dropped slightly back, yet felt so good and positive and excited for the bike.
"I had a good day on the bike, with a strong will to push myself more. I really committed and felt good. I lost all my nutrition about 30min in, but it was another challenge to overcome then bam! I got a penalty for what I'm told was drafting.
"The run felt great for the first 1.5km and then 'oh no, my calf is gone!' and I had a moment.
"But somehow I managed to control the anxiety and discomfort and tolerated it. I walked every aid station and some of the bridges to off-load the muscles.
"I can't believe I could hold off Penny Slater. I had to work so hard for this one."
Ironman Texas: Women's results
- Kat Matthews
- Penny Slater
- Lotte Wilms
- Hannah Berry
- Alice Alberts
Photo credits: Kyle Rivas / Getty Images for IRONMAN
