Couples and Dufner lead Masters by one as Woods slips back

(CNN) -- Former Masters champion Fred Couples fired a five-under par round of 67 to claim a share of the lead with fellow American Jason Dufner at the Masters on Friday.

The 52-year-old, whose only major win came at Augusta National in 1992, helped himself to seven birdies including a run of three at the 7th, 8th and 9th holes.

A superb back nine which included birdies at the 15th and 16th saw Couples shoot the lowest score of the day and finish five-under par after two rounds.

"It was a very, very magical day. I'm going to be right there with everybody on the weekend," Couples said.

"If I come out here and play my game the best I can, I'll have a shot," he added.

Dufner, runner-up at the PGA Championship last August, carded a two-under 70, go with his opening round 69.

The pair lead by one a chasing pack that includes overnight leader Lee Westwood and Rory McIlroy.

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Westwood was heading for a one-under par round of 71 but a double bogey at the 18th spoilt a steady round after his impressive showing on Thursday.

McIlroy compiled a composed 69, which included five birdies, but dropped shots at the 10th and the 17th took a little bit of the shine off his round. Nevertheless, the Northern Irishman was satisfied with his progress.

"I'm right where I want to be. I put myself in position to have a chance to win this tournament again," McIlroy said.

South Africa's Louis Oosthuizen is also one shot off the lead after an even-par round of 72 as is Spain's Sergio Garcia, who shot a four-under par 68, and America's Bubba Watson who carded a 71.

But Tiger Woods' challenge for a fifth Green Jacket faded on Friday as he struggled to a three-over par round of 75, eight shots off the lead.

The current world No.1 Luke Donald may also struggle to mount a challenge at the weekend. With three holes left to play of his second round he was also three-over par.

Reigning champion Charl Schwartzel is on the same score after completing a disappointing round of 75.

But an exciting weekend is guaranteed with 16 players within three shots of Couples and Dufner, including Phil Mickelson whose four-under par 68 lifted him to two-under par.

One shot ahead on three under par is a group of four players including America's Matt Kuchar (70) and Scotland's Paul Lawrie who shot a 72 to go with his opening 69.