He should, too, because he has been married to the US Women's Open leader for nine years.

Duane Smith is the only caddie Sarah Jane has known and he has been at her side every step of the way, on and off the course, since she turned pro in 2004.

They have known each other since childhood in Queensland, and started dating after playing a mixed foursomes event together when they were 18.

After Duane's aspirations of becoming a PGA Tour player hit the wall, he turned his focus to caddying for his then girlfriend.

It hasn't always been an easy road.

Smith has never won an LPGA event and Duane has on occasion wondered whether he is the right man for the job.

"I feel sometimes (during) the bad times someone else would be able to get her through it maybe better than I can, because we're always around it together," he said.

"We have our bad days, but for the most part it works. For the most part she's really cruisey."

RIGHT: Mrs and Mr Smith hard at work during the US Women's Open. PHOTO: Getty Images.

Duane was speaking after his 33-year-old wife carded a second straight 67 to leave the field in her dust in the second round at Shoal Creek.

Sarah Jane had a four-stroke clubhouse lead over fellow Australian Su Oh with half the field yet to complete the round.

Duane is an experienced caddie these days, but it was not always thus.

He recalls some "really stupid mistakes" early on, including one where he gave Sarah Jane the wrong yardage during the first round of an LPGA event when they had not had a chance for a practice round.

"We got to this par-three and it played way downhill," he said. "I totally messed up the number. It (the tee shot) went over the green, nearly hit a cow in this farm over the back.

"It probably would have been smarter for her to have had someone else from the beginning who knew what they were doing."

These days it is verbal mistakes Duane most wants to avoid.

"We know little things that push each other's buttons, and as long as I don't do that we're OK," he said.

– Andrew Both, Reuters