Woods is aware that his putter could cost him this week
Tiger Woods will have to equal the biggest 36-hole comeback in US Open history if he is to defend his crown and win a 15th major title this week.
The 33-year-old fired a one-under 69 in Saturday's second round at Bethpage Black to finish three-over, 11 strokes off the pace of US leader Ricky Barnes.
But Woods says he will have to improve his putting if he is to go close.
"The putts I hit well didn't go in and the putts I hit poorly weren't even close," said the world number one.
"I need to make a few more putts. And get it rolling."
If Woods is to edge to within three major victories of Jack Nicklaus's record haul of 18, he will have to emulate Lou Graham, who came from 11 shots back in the final two rounds to win the 1975 US Open at Medinah.
"I'd like to. There's no doubt. I'm hitting it well enough," Woods said.
"Unfortunately, my score doesn't reflect how I've been playing. But you never know. I've got 36 more holes over the next probably three days.
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