Centurion Saif played through the pain during Steelbacks win

The talented all-rounder smashed 136 from just 101 balls to help the Steelbacks hunt down Essex Eagles' 343 for nine, winning by three wickets with two deliveries to spare.

At one point, Zaib had to retire hurt, but he returned to the middle to provide important extra ammunition for Northants.

And eventually, thanks to some late heroics from James Sales (34no) and Nathan Buck (10no), the County got the job done in front of a record Royal London One Day Cup crowd.

“When I scored a few fifties in the T20s, we didn't quite get over the line, but it was nice to contribute to a winning team," Zaib said.

"I hadn’t scored a List A 50 in my career either, so it was nice to get over that hump and actually make it a big one.

"It would have been nice to stay there throughout, but it was nice to at least get back out there.

"I couldn't feel my legs. It was probably the single most pain I've ever had in my life. But I think I should be okay for the next few weeks.

"And yeah, I’ll just get plenty of rest and a lot of water on board.

"I think it might have been the sun and stuff like that, just cramping up my legs, but I think I should be okay."

Zaib says it was fully his decision to return to the game after it initially looked like his day was done.

“He (head coach John Sadler) never really pressured me to resume my innings, to be honest," Zaib said.

"It was solely my decision whenever I felt like I could actually walk because I lay down in the changing room for about half an hour afterwards, just trying to shake everything out of my system.

"And literally as soon as I could get up and walk, got a lot of Tubigrip on my legs and just got back out there and tried to get us over the line."

Zaib was eventually dismissed by Jamal Richards, but Northants held their nerve thanks to the brilliance of Sales and Buck.

“Bucky has been whacking it every time I see him so that was no surprise," Zaib said.

"He also bowled well early on (Buck took five for 59) and got his first List A five-fer. I think that was a big relief for him as well.

"Junior (Sales), he’s a very fine cricketer and he showed what he's made of. He's got the full package really, he can bat, bowl and field."

Northants had lost their One Day Cup opener at Yorkshire Vikings.

But they got their campaign up and running against the Eagles, and next up is a trip to Hampshire on Tuesday (start time 11am).

“It was pleasing to get the win," Zaib said.

"It's always nice to chase down 300 plus and we did it with a couple of balls to spare and I think we had a bit more in the tank.

"But it was just an amazing feeling to get over the line.”