An ailing Michelle Wie withdrew after nine holes of her second round in the US Tour's John Deere Classic in Illinois last night.

The 16-year-old, down near the rear of the field after an opening 77, complained of pains in her stomach and shortage of breath in the hot and humid conditions and, after trying to play on at first, accepted medical advice to pull out.

Struggling to keep up with the pace of play, Wie, making her fifth appearance on the men's circuit, somehow managed a birdie on the eighth hole, but was seen by a doctor coming off the next tee.

With her parents watching anxiously, Wie double-bogeyed the hole to drop to eight over, then spoke to them and told officials she was going to stop.

Earlier, a six-birdie 66 had re-ignited Justin Rose's hopes of grabbing the last available place in next week's Open.

The spot is available to the leading non-exempt player providing they finish in the top 10 on Sunday.

Rose resumed down in 93rd place, but was all the way up to 18th when he reached halfway on the five-under-par mark of 137.

Leaders at 10-under were Americans Joe Ogilvie and Australian John Senden, while Swede Daniel Chopra was one behind after adding a 69 to his pacesetting opening 64.

Wie's next two scheduled appearances are in Europe at the Evian Masters in France and the Women's British Open.

Meanwhile, Tiger Woods believes three or four practice rounds will complete his preparations for the Open, which starts next Thursday at Hoylake, a venue he has never previously played.

The Royal Liverpool Golf Club last staged the world's oldest golf championship in 1967 when Argentina's Roberto de Vicenzo triumphed by two shots over Jack Nicklaus.

"We play around the world and learn different golf courses in a day or two," the 30-year-old Woods said. "It's part of playing golf. I honestly don't know anything about Royal Liverpool, but I'll play three or four practice rounds and that should be enough time to prepare.

"The key is to make sure you do your homework and find out what the golf course will allow you to do."