Organisers of The Open Championship have decided to change the schedule for Saturday's third round in view of the forecast for heavy rain and thunderstorms around Hoylake near the city of Liverpool.
Play will begin at 0900 local time, with a simultaneous shotgun start on the front and back nines, in an effort to dodge the bad weather.
"We have taken a number of decisions regarding tomorrow's play to maximise the chances of completing the championship on time," said Royal & Ancient (R&A) executive director of rules David Rickman.
"These are that play is scheduled now to commence at 8am," he added in a prepared statement that was later corrected to 9am.
"Play will be in groups of three and we will utilise a two-tee start using the first and 10th tees. These measures combined give us the potential to accommodate up to five hours of delay and still complete the third round tomorrow evening."
Rickman said it would be the first time a shotgun start would be used in the third round of golf's oldest major.
"All the professional advice that we are receiving tells us that significant disruption is highly likely and it's only responsible of us to react appropriate to that," he explained.
It means a start thee and half hours earlier than normal for Northern Ireland's Rory McIlroy, who leads the tournament by four shots from American Dustin Johnson after a pair of 66s.
He would normally have been due out at 2:30pm with all the players who made the cut traditionally starting from the first hole.
Rickman added: “The forecast I have seen predicts that the bad weather will be arriving very early in the morning, possibly as early as 2am (Saturday morning). It is forecast potentially to last through much of the morning with a four-hour window of much improved conditions in early afternoon, with the possibility of further thunderstorm activity coming in late tomorrow evening.”
Tiger Woods goes out at the same time as McIlroy from the 10th tee. He is 14 shots behind McIlroy, and playing for pride over the final two days.
Third-Round Tee-Off Times (All BST). All players GB & Ireland unless stated.
09:00 Jason Dufner (US), Keegan Bradley (US), Phil Mickelson (US)
09:11 Thongchai Jaidee (Tha), Gary Woodland (US), DA Points (US)
09:22 Kristoffer Broberg (Swe), David Hearn (Can), Graeme McDowell
09:33 Branden Grace (SA), Hideki Matsuyama (Jpn), Byeong-Hun An (Kor)
09:44 Shane Lowry, Stephen Gallacher, Matteo Manassero (Ita)
09:55 David Howell, Justin Rose, Bill Haas (US)
10:06 Edoardo Molinari (Ita), Thomas Bjorn (Den), Marc Leishman (Aus)
10:17 Adam Scott (Aus), Victor Dubuisson (Fra), Jimmy Walker (US)
10:28 Robert Karlsson (Swe), Marc Warren, Jim Furyk (US)
10:39 Louis Oosthuizen (SA), George Coetzee (SA), Charl Schwartzel (SA)
10:50 Sergio Garcia (Spa), Rickie Fowler (US), Ryan Moore (US)
11:01 Dustin Johnson (US), Francesco Molinari (Ita), Rory McIlroy
Starting at hole 10
09:00 Chris Rodgers, Gregory Bourdy (Fra), Ben Martin (US)
09:11 Darren Clarke, Matt Kuchar (US), Hunter Mahan (US)
09:22 Kevin Stadler (US), Chris Kirk (US), Martin Kaymer (Ger)
09:33 Billy Hurley III (US), John Senden (Aus), Chris Wood
09:44 Matthew Jones (Aus), Brooks Koepka (US), Paul Casey
09:55 Henrik Stenson (Swe), Angel Cabrera (Arg), Ryan Palmer (US)
10:06 James Mcleary, Brian Harman (US), Charley Hoffman (US)
10:17 Kevin Streelman (US), Brendon Todd (US), Brandt Snedeker (US)
10:28 Zach Johnson (US), Jason Day (Aus), Kevin Na (US)
10:39 Koumei Oda (Jpn), Thorbjorn Olesen (Den), Stewart Cink (US)
10:50 Tom Watson (US), Luke Donald, Matthew Every (US)
11:01 Tiger Woods (US), Jordan Spieth (US), Rhein Gibson (Aus)
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- Rory McIlroy