Alistair Brownlee incurred a penalty before withdrawing due to injury in a nightmare day at the gruelling T100 Singapore.

The 35-year-old was competing in the second stage of eight in the revolutionary new T100 World Tour, pitting 20 of the world’s best triathletes against each other over 100km with $7 million on the line.

Brownlee blew up on the run leg to finish fifth in the opening race in Miami and had a tough time of it in blistering heat in Singapore’s Marina Bay.

In sweltering overcast conditions, Brownlee was among the leaders in the 2km swim.

Once on the bike, there was plenty of chopping and changing early on before eventual winner Youri Keulen opened up a minute lead on the chasing pack that included Brownlee.

As the chase group entered the second transition, a late dismount from Brownlee meant the double Olympic champion was handed a 30-second penalty.

On the ruling, Brownlee said: “Rules are rules. We can’t argue the merit of the rules cause you’re not going to get any advantage. It looks like it was over the line so I have the penalty. I don’t know if it was over the line.”

Serving the penalty after making it to the podium places, the Brit was soon reduced to a walk, then stretched his calf, before succumbing to a DNF.

On the serious-looking injury, Brownlee said: “As soon as I hit the ground off my bike, I pulled something in my ankle and I started running and I thought it kind of went away. But when I started running again after I stopped, it got really sore and I can hardly walk now.”

Dutch wildcard Keulen went on to claim his maiden T100 victory, while American comeback specialist Sam Long charged from last on the swim to finish second and Belgian Pieter Heemeryck finished a very creditable third.

The T100 Tour now heads to San Francisco on 7-8 June.