The challenge of picking the Kentucky Derby winner out of a field of 20 3-year-olds is imposing. Heading into the first Saturday in May at Churchill Downs this week, just figuring out which horse will be favored is tough enough.

Journalism emerged as the clear favorite in last year’s Kentucky Derby after winning the Santa Anita Derby and posting big speed figures in his last two prep races. Journalism, of course, wound up second to Sovereignty.

A handful of contenders could be the post-time favorite this Saturday. The morning-line choice, Arkansas Derby winner Renegade, drew the tricky inside post. The top three finishers in the Florida Derby — Commandment, The Puma and Chief Wallabee — finished within a length of each other. Further Ado romped in the Blue Grass Stakes, posting the field’s top speed figure.

Renegade was extremely impressive swooping the field and pulling away in the Arkansas Derby. He’s a deep closer, so the inside draw may not be as much of a disadvantage as usual. However, jockey Irad Ortiz Jr. will have to thread his way through the field to get into position to take the lead during the stretch run.

Commandment has won his last two races by slim margins, sneaking up the rail to beat Chief Wallabee in the Fountain of Youth, then closing from the outside to catch The Puma in the final stride of the Florida Derby.

The Puma got the jump on Commandment in that slow paced race, while Chief Wallabee awaited room along the inside, then swung out to finish just a half length behind. Clearly, there’s not much separating that trio.

Further Ado pulled away from a mediocre field during his Blue Grass romp but the speed figure for the race stands out. The mystery regarding Further Ado is whether he’s a ‘horse for the course’ — his two best races have come over the Keeneland track.

There are a few others to consider. So Happy won the San Anita Derby and while the California horses seem a cut below this year, his speed figure was competitive. The X factor is Danon Bourbon, a Kentucky bred who won all three of his races in Japan. Emerging Market captured the Louisiana Derby in just his second career start.

However, the winner is likely to come out of the first group of five. Which one? I’ll give a slight nod to Chief Wallabee.

Trainer Bill Mott and jockey Junior Alvarado should be familiar to race fans — they were in the winner’s circle with Sovereignty last year.

Chief Wallabee doesn’t have as much experience as Sovereignty coming into this year’s race. Sovereignty won a stakes race at Churchill Downs as a 2-year-old. His stablemate didn’t even debut until January.

Mott is making an unconventional move for the Derby, adding blinkers to Chief Wallabee to help with his focus. Blinkers tend to make horses run closer to the pace, which could be pretty fast on Saturday.

However, the horse has posted sharp works since the addition of blinkers. Mott had Sovereignty ready to peak in the Derby last year — why can’t the Hall of Famer pull off the same feat?

Renegade’s running style could make it difficult for him to win but I see him as the most likely entrant to run in the money. Further Ado could work out a nice stalking trip. I’m not sure he’ll hold off all the closers.

Emerging Market is being ignored mainly due to his lack of experience but he could be the most talented horse in the race. He’s one to strongly consider in exotic wagers.

Top five: 1. Chief Wallabee; 2. Renegade; 3. Further Ado; 4. Emerging Market; 5. Commandment.