Hostile Grins has not raced since he won the Wairio Cup on December 18 but he won a trial at Ashburton nine days ago.
McKay is in form and he is racing on his favourite track. He won the Reefton Cup at his last start after a win at Westport.
He won a double at this meeting in 2009 and he was successful at Waterlea in June.
River Black, who heralded a successful 3yr-old season with a fresh-up win at Omakau, is in race 8 today A last-start win over a mile in 1.56.5 at Ashburton has Tatijana Bromac high on the list of fancies for the heat of the Sires' Stakes at Waterlea today.
The Rocknroll Hanover filly, trained by Mark Purdon and Grant Payne, has won two of her three starts.
Miss Elsie, a smart filly, is drawn to be prominent.
Tony Herlihy has the chance for another feature-race win at Cambridge when he drives Russley Rascal in the $45,000 Futurity Stakes tonight.
Herlihy drove Pembrook Benny to win the Flying Mile there last Friday.
Russley Rascal ran third to Lightning Raider and Five Star Anvil at Alexandra Park at his last start on December 17.
The drive became available when trainer Mark Purdon opted for Highview Tommy, who ran fourth to Pembrook Benny last Friday.
