This is one tough Kentucky Derby to figure out, sort of like 2009. And there’s a good chance of rain on Saturday for the 137th edition.

Remember over the past three decades only four favorites have won — all in the 21st Century. Big Brown was the last in ’08; Street Sense,’07; Smarty Jones, ’04; and Fusaichi Pegasus, ’00.

So let’s get it on starting with the pretenders, including horses that have only one victory or no stakes triumphs and haven’t won or performed well on dirt.

Dubai invader Master of Hounds has only a single triumph and that was on grass. Blue Grass winner Brilliant Speed and Spiral victor Animal Kingdom are winless on dirt.

Stamina is important for a 3-year-old going 1 ¼ miles. That’s why I’m not using in exotic wagers horses that have shown they don’t want to go that far.  Comma to the Top, Decisive Moment, Derby Kitten, Mucho Macho Man, Santiva, Stay Thirsty, Twinspired and Watch Me Go haven’t scored beyond 1 1/16 miles.

Now for the Maybes:

Shackleford and Pants on Fire have one thing in common – they love to be in front fairly early. So pace-wise each could be the downfall of the other. But advantage Shackleford for two bullet works at Churchill Downs.

Twice the Appeal’s speed figures are on the low side, but he gets a boost when the winning rider in three of the past four in Louisville climbs aboard – Calvin Borel.

Midnight Interlude has raced four times this year, winning the Santa Anita Derby, but lacks a 2-year-old foundation. He could score, I guess, but I won’t have any money on him.

Nehro has been the Derby Buzz Horse after running second in the Arkansas and Louisiana derbies. His speed figures aren’t bad, but I don’t go for maiden-only winners in the Big Derby.

The Main Contenders are:

Uncle Mo has the highest speed rating of the 20 starters, but that was last year winning the Breeders’ Cup Juvenile at Churchill Downs. Word is the son of Indian Charlie has not fully recovered from a GI tract infection discovered in mid-April after running third in the Wood Memorial. See how he looks in the post parade if he makes the race. The early 9-2 second choice drew post 18.

Soldat: If the track comes up sloppy I shall key the son of War Front in exotics because he has the second highest speed figure while winning in the slop in a Gulfstream allowance contest at 1 1/8 miles. I don’t like post 17, which has never produced a winner. But I like 12-1. If the pace is on the slow side he benefits. He will be in several of my exotics no matter the track conditions.

Archarcharch: The Arkansas Derby victor has been no less than two lengths behind during his stretch runs in all three triumphs. But drawing the inside post is a big negative. However, his tactical speed is a plus. The son of Arch still stands a chance and I hope the early 10-1 odds don’t float down.

Dialed In: The Florida Derby winner, who breaks from post 8, has performed consistently on the Road to the Roses. Trainer Nick Zito loves the son of Mineshaft who also captured the Holy Bull. If he doesn’t encounter too many traffic problems in the stretch he can win it all and give Zito his third Derby champ. He’s in my exactas and trifectas despite being the morning line 4-1 favorite.