* Four players share halfway lead
* Only three players break par in second round
* More than 100 balls end up in the water (Adds second round)
By Steve Keating
DORAL, Florida, March 7 (Reuters) - American Hunter Mahan eagled his penultimate hole to grab a share of the halfway lead at the WGC-Cadillac Championship on Friday as the Blue Monster showed its true colours, with more than 100 golf balls ending up in the water.
On a brutal day that some players described as a survival test, Mahan eagled the par five eighth in fading light for a second round of two-over 74 that left him tied for the lead with his compatriots Dustin Johnson (74), Patrick Reed (75) and Matt Kuchar (74) at one-under par.
Lurking one shot behind them were another four players: Northern Irishmen Rory McIlroy (74) and Graeme McDowell (71), Italian Francesco Molinari (75) and Welshman Jamie Donaldson, who posted the low round of the day with a two-under 70.
Long regarded as one of the PGA Tour's great layouts, the Blue Monster course underwent a massive $251 million renovation that made it even more frightening and almost unplayable when the winds whipped across the sprawling layout on Friday.
With most players arriving early to complete their rain-delayed opening rounds, exhausted golfers slumped off the course after a day of battling brutal winds and fatigue.
Only three players managed to break par during a wild second round that saw more than 100 balls find a watery grave while the average score was four-over 76. (Editing by Julian Linden)