American Jason Dufner shot a nine-under-par round of 63 to move to the top of the leaderboard at the delayed RBC Canadian Open, but it was Mark Calcavecchia who was in record-breaking form at the Glen Abbey Golf Club in Oakville.

Heavy rain and lightning on Friday meant the whole field needed to complete their second rounds on Saturday and it was Dufner who fared the best as he moved on to 13 under.

It could have been even better for the 32-year-old, who has never won a PGA Tour title, but he bogeyed the 17th having previously racked up eight birdies and an eagle.

"I played very well, hit a lot of fairways, a lot of greens," Dufner said afterwards.

"It started raining at the end, conditions got a little tougher, but 63 is a pretty good score, and leading after two rounds is always great."

All of the players were able to complete their second rounds, but the heavy rain set in once more forcing the postponement of the third round until Sunday.

Tour officials are hoping the weather will be more favourable then and allow 36 holes to be played.

Jerry Kelly and Scott Verplank are one behind Dufner on 12 under after both fired 67s while Australia's Nathan Green, who scored a 65 in the second round, and Peter Tomasulo of the US are on 11 under.

A group of six players are three off the pace, including Colombia's Camilo Villegas, South African Retief Goosen and Martin Laird of Scotland.

Calcavecchia, who began his second round on the back nine, was tied for 17th on eight under after his 65 today, which included nine consecutive birdies from the 12th hole to the second - a PGA Tour record.

That took the American to 10 under par but the gloss was taken off his achievement slightly by bogeys at the fourth and eighth.

Anthony Kim is usefully poised at nine under while England's Luke Donald, who finished tied fifth at the Open last weekend, comfortably made the cut on four under.

John Daly, however, was among those to miss out, the colourful American struggling to a level-par 72 today to finish at five over.

Collated second round scores & totals (USA unless stated, par 72):

131 Jason Dufner 68 63

132 Jerry Kelly 65 67, Scott Verplank 65 67

133 Peter Tomasulo 65 68, Nathan Green (Aus) 68 65

134 Kevin Na 63 71, Bob Estes 67 67, Pat Perez 67 67, Retief Goosen (Rsa) 65 69, Martin Laird (Sco) 65 69, Camilo Villegas (Col) 63 71

135 Anthony Kim 69 66, Tim Herron 67 68, Scott Sterling 67 68, Briny Baird 72 63, Y.E. Yang (Kor) 69 66

136 Michael Letzig 69 67, Mark Calcavecchia 71 65, Jimmy Walker 66 70

137 Mike Weir (Can) 71 66, Ken Duke 66 71, Kevin Sutherland 68 69, Stephen Ames (Can) 68 69

138 Patrick Sheehan 68 70, Charles Warren 70 68, Chris Riley 68 70, John Merrick 70 68, Billy Mayfair 69 69, Lee Janzen 68 70, Parker McLachlin 66 72, Daniel Chopra (Swe) 70 68, Dean Wilson 68 70, Corey Pavin 68 70, Jay Williamson 70 68

139 Scott McCarron 68 71, Graham Delaet (Can) 73 66, Harrison Frazar 68 71, Webb Simpson 71 68, Steve Elkington (Aus) 68 71, Mark Wilson 68 71, D.A. Points 68 71, Steve Marino 70 69, Joe Durant 65 74, Mike Grob 70 69, Leif Olson 68 71, Nicholas Thompson 73 66

140 Jeff Quinney 71 69, Christopher Baryla (Can) 69 71, Jamie Lovemark 74 66, Derek Fathauer 66 74, David Peoples 67 73, Dicky Pride 70 70, Bryce Molder 71 69, Frank Lickliter II 68 72, Brendon De Jonge 67 73, Andres Gonzales 71 69, Darron Stiles 69 71, Scott Piercy 71 69, Jason Day (Aus) 70 70, Kevin Streelman 72 68, Kevin Stadler 70 70, J.B. Holmes 73 67, Luke Donald (Eng) 71 69, Brandt Snedeker 73 67

141 Aron Price (Aus) 72 69, Omar Uresti 72 69, Joe Ogilvie 72 69, Lucas Lee 71 70, Steve Lowery 67 74, Cliff Kresge 69 72, Jeff Klauk 71 70, Ryan Palmer 69 72, Bo Van Pelt 74 67, David Mathis 71 70, Jonathan Byrd 72 69, Bob Heintz 70 71

-------------------The following players failed to make the cut-------------------

142 Michael Bradley 72 70, Brad Adamonis 71 71, Casey Wittenberg 72 70, Greg Chalmers (Aus) 71 71, Stuart Anderson (Can) 71 71, Brian Bateman 69 73, Chez Reavie 73 69, Dustin Risdon 71 71, Brad Faxon 74 68, Sean O'Hair 73 69, Arjun Atwal (Ind) 75 67, Bill Haas 73 69, Roland Thatcher 72 70, Craig Barlow 70 72, Tommy Gainey 69 73

143 Spencer Levin 70 73, Rafael Gomez (Arg) 71 72, Jonathan Kaye 72 71, Jeff Overton 70 73, Chris DiMarco 71 72, Wil Collins 74 69, Bubba Watson 75 68, Matt Hill 70 73, Todd Hamilton 69 74, Tom Pernice Jnr. 74 69, Nick O'Hern (Aus) 73 70, Charlie Wi (Kor) 70 73, Jay Delsing 69 74, Steve Allan (Aus) 70 73

144 Kris Blanks 75 69, Vaughn Taylor 74 70, John Senden (Aus) 72 72, Troy Kelly 71 73, Peter Lonard (Aus) 73 71, Jason Gore 73 71

145 Hugo Leon 74 71, Mathias Gronberg (Swe) 70 75, John Mallinger 73 72, Matthew Jones (Aus) 72 73, Billy Andrade 73 72, Brian Vranesh 73 72, Ryuji Imada (Jpn) 73 72, Glen Day 71 74, Johnson Wagner 70 75, Tyler Aldridge 72 73

146 Colt Knost 70 76, Eric Axley 74 72, Brendon Todd 72 74, Bryan Decorso (Can) 71 75, Ian Leggatt (Can) 74 72, Rick Price 72 74, James Oh (Kor) 74 72

147 Kent Jones 68 79, J.P. Hayes 72 75, Troy Matteson 76 71, Cam Burke (Can) 74 73, Matt Weibring 73 74

148 Graham Baillargeon (Can) 75 73, Wes Heffernan (Can) 69 79

149 John Daly 77 72, Trevor Immelman (Rsa) 71 78, Mauricio Molina (Arg) 72 77

151 Richard Lee (Nzl) 73 78, Matthew Borchert 76 75

152 Mathew Goggin (Aus) 73 79, Nick Taylor (Can) 79 73

153 Kyle German (Can) 75 78

156 Andrew Parr (Can) 72 84

WD: 72 Jeff Maggert

73 Greg Owen (Eng), David Gossett, Robert Garrigus

74 Tag Ridings

75 Matt Bettencourt

76 Aaron Baddeley (Aus)

77 Carl Pettersson (Swe)

78 Mark Brooks, Brian Davis (Eng)