The opening day of the Cheltenham Festival has gone ahead despite overnight frost, but the start of racing was delayed by 35 minutes.
The first race went off at 14:05 GMT and the Champion Hurdle, the day's main race, was put back to 16:00.
But the Cross-Country Chase, pencilled in for 17:45, will now run on Thursday at 17:15 after an inspection.
That means the opening day programme has been reduced to six races, from the seven originally scheduled.
The course has been protected by frost covers with temperatures feeling as low as -11C with the wind chill factor.
Course spokesman Andy Clifton told the BBC: "Around 95% of the track is absolutely fine under the covers, there are just one or two areas that are causing a small amount of concern.
"The frost covers do their job so where they haven't been, it will be pretty cold."
An estimated 230,000 spectators are expected over the four days.
Frost covers went down at the weekend on the old course track, which is used for the first two days, and the new course - which stages racing on the final two days.
The tarpaulin-style covers - across an area of about 65 acres, or the equivalent of 45 football pitches - were lifted on the old course this morning.
REVISED DAY ONE SCHEDULE
2.05 William Hill Supreme Novices' Hurdle (Grade One) 2m 110y £120,000
2.40 Racing Post Arkle Challenge Trophy Chase (Grade One) 2m £150,000
3.20 JLT Specialty Chase (Handicap) (Grade Three) 3m 110y £90,000
4.00 Stan James Champion Hurdle (Grade One) 2m 110y £400,000
4.40 OLBG Mares' Hurdle (Grade Two) 2m 4f £85,000
5.15 Pulteney Land Investments Novices' Handicap Chase (Listed) 2m 4f 110y £60,000