American golfer Phil Mickelson has given two children running a drinks stall a $99 (£65) tip after buying a glass of lemonade.

The world number 19 bought the drink, which was priced at $1, on his way to the Memorial Tournament in Ohio after six-year-old Roland van Karsen and his eight-year-old sister Elise had set up the stall outside the golf course.

Roland told the Columbus Dispatch: "All we were doing was sitting here, and all we saw was this white car drive up, and it was close, and he said 'Can I have a glass of lemonade?' and all it took was one little thing for him to give us a good tip."

Their mum added: "We didn't take any pictures, we didn't get any autographs. It happened so fast that we were kind of stunned. What a great guy, though, right? So generous and the kids will have a memory like that forever."

The Van Karsens run the stall every year during the tournament, normally earning $15 per day.