"How long does it take to build the tennis courts?"
The two girls from the event operation do a quick recap and say, "About 36 to 40 hours."
And that's not just the courts. Once the event team is handed over the space, they get the whole arena ready in less than two days.
One step into the tennis stadium at the London O2 and you understand it's a special event, but the speed with which the arena dresses up for the season-ending ATP world tour finals is simply astounding.
"The Gorillaz (British band) had a concert on Tuesday.
“We got the arena in our hands only on Wednesday morning, and basically we had to get the courts ready for players to practice on Friday," said Lottie Cresswell, from the event operations team.
To begin with the tennis courts, the process sounds simple. Wooden planks, of 38mm thickness are first laid, they are then coated with a six-inch layer of acrylic paint.
The heaters are turned on for the paint to dry, and then coated with another two layers of the paint.
One dry, the lines are painted on, net posts suspended, since they cannot be drilled into the court, and the easy-to-maintain surface ready for a week's action.
The temporary screens are suspended, the lights put into place and the preparations hurried up for the event. Apart from the seats, everything is built up from scratch.
While the tennis courts sit in the focus of bright lights, the rest of the area is almost blacked out.
Chris Kemode, the brain behind it all, went for it to make the atmosphere more like a boxing match.
Prime-time entertainment, or as the operations team likes to call it "modern-age tennis."
From the outside, the O2, with spokes of light sticking out of the dome, looks like a spaceship under construction. On the inside, it's a model of technological efficiency.