BEST HEADS DOWN UNDER Sheikh Mohammed is to send four stallions to Australia, including last year`s 2000 Guineas winner King`s Best.The quartet, who also include 1997 Dubai World Cup winner Singspiel, will stand at Robert Sangster`s Collingrove Stud in New South Wales for the 2001 breeding season down under.Darley`s southern hemisphere manager Oliver Tait said on the Darley website: 'Darley at Collingrove is an indication of our commitment to the Australian market.'Joining King`s Best and Singspiel will be Lujain and Xaar, who has previously shuttled between Kildangan Stud in Co. Kildare and Arrowfield Stud in Australia.