When Pacquaio get the courage to face Mayweather, what round do you think he would quit?

We know Pacquaio doesn't have a lot of heart. Pacqaio quit on Morales after the cut and he stopped fighting hard. Pacquiao also quit on Marquez on the first fight, against Singurat, and against Torrecampo with simple body shots. Mayweather would never quit on those type of weak situations. We know Pacquaio will probably quit against Mayweather after he gets frustrated with missing so many punches. He will quit just like De La Hoya did against Trinidad in the later rounds. The question is which round would Pacquaio quit?