The World Baseball Classic has had more thrills and plot twists than Warren Beatty and Faye Dunaway opening an envelope at the Academy Awards. Winners have become losers, losers have become winners, and the unexpected has become expected.

No more round-robin pool play. We’ve reached the semifinals, with three games in three days at Dodger Stadium. Puerto Rico defeated the Netherlands to reach Wednesday's championship game. The United States plays unbeaten Japan on Tuesday for the other spot in the title clash (all games at 9 p.m. ET on MLB Network, with ESPN Deportes and WatchESPN providing Spanish-language coverage). If only we could coax Vin Scully out of retirement to call a few innings.

Here’s a viewer’s guide to what to watch:

So explain those rules again. Now that we’re out of pool play, we don’t have to worry about the complicated tiebreaking process. There are, however, a few rules to be aware of:

1. Pitchers are now allowed to throw a maximum of 95 pitches, up from 80 in the previous round. If a pitcher throws at least 30 pitches, he must sit a day, so this could come into play in the U.S.-Japan game, without a day off before the championship.

2. Starting in the 11th inning, the team at bat will have runners on first and second base to start the inning.

3. Instant replay will be used as it is in MLB, except there is no managerial challenge available.

How is Puerto Rico unbeaten? They’ve been the most impressive team in the tournament, outscoring their opponents 55-19, including two blowouts over Venezuela and 3-1 and 6-5 wins over the Dominican Republic and U.S., respectively, in the second round before outlasting Netherlands in extra innings. Carlos Correa has led the offense with 3 home runs, 9 RBIs and a .400 average, while Carlos Beltran is hitting .476 and Francisco Lindor .435 with a couple of home runs.

The surprise has been a pitching staff that, on paper, lacked the depth, especially in the bullpen, of the U.S. or D.R., but manager Edwin Rodriguez has mixed up his starting pitchers and deftly managed the relievers. Mariners closer Edwin Diaz gives the staff a legitimate MLB closer as the ninth-inning guy.

How is Japan 6-0? Let’s be honest: Japan faced a much easier road to the semifinals, especially with Korea getting knocked out in the first round. The Cuban team was much weaker than past editions, so that left Japan with only one reasonably tough opponent in six games, and it beat the Netherlands in 11 innings, taking advantage of the two-baserunner extra-inning rule to score two runs.

That doesn’t mean the Japanese aren’t a threat to win their third WBC in four tournaments. They’ve hit 10 home runs in their six games, although let’s see if that power translates from the friendlier confines of the Tokyo Dome to Dodger Stadium. Without a hard-throwing ace like Daisuke Matsuzaka or Yu Darvish to rely upon, as the team did in 2006 and 2009, manager Hiroki Kokubo has turned to his bullpen. Ryo Akiyoshi, Kazuhisa Makita and Yoshihisa Hirano each have appeared in five games, with Makita picking up a win and two saves. A former starter for Seibu, Makita transferred to the bullpen in 2016 and recorded a 1.60 ERA, although he wasn’t the team’s closer.

How does the U.S. shape up? The most difficult thing for manager Jim Leyland is outlining a pitching strategy. Tanner Roark will start against Japan, while Marcus Stroman is lined up to get the ball if the U.S. reaches the final. Roark has pitched just once in the tournament, on March 11 against the D.R., and struggled with his command, allowing three runs and two walks in 1 1/3 innings. Stroman gave up six hits to start the game against Puerto Rico in the second round, although to be fair, a few of those were seeing-eye singles, and he settled down after that.

Roark, who had a 2.83 ERA for the Nationals in 2016, is certainly a fine starter, although the decision to start him over Chris Archer is odd, considering Archer had expected to return to the squad. Archer even pitched in a minor-league game Thursday to stay on schedule to pitch in the championship round. Instead, he was told to remain with the Rays and will start Wednesday in the Grapefruit League.

Perhaps Leyland felt a need to give Roark some work. Nationals manager Dusty Baker was upset when he woke up Sunday morning and learned that Roark hadn’t pitched in Saturday’s game, after being told Roark would be used over the weekend. Baker also was upset that Daniel Murphy hasn’t played much, with just six at-bats in six games.

The U.S. did call up Mark Melancon from its pitching pool for more bullpen depth. Without a day off between the semifinals and final, the likelihood is that Leyland wants to avoid using any of his relievers on back-to-back days, although since we’re deeper into spring training now, I wouldn’t rule out that possibility -- after all, everyone still wants to win, and there’s no reason to hold, say, Andrew Miller back if he throws 15 pitches in a semifinal victory.

Give me a player to watch on each remaining team. OK, let’s do it.

Puerto Rico: You can’t ignore Correa, who also has played an excellent third base, but Mets right-hander Seth Lugo is on schedule to start the championship game and could be the most important player on the roster. He started the Friday win over the U.S., allowing three runs in 5 2/3 innings, giving up home runs to Buster Posey and Adam Jones.

Japan: Yoshimoto Tsutsugoh. The 25-year-old left-handed slugger led Japan’s Pacific League with 44 home runs and has three home runs in the WBC. You have to think we’ll see Miller face him at some point.

United States: Eric Hosmer. It’s been a bit of surprise that Hosmer has basically become the first baseman over Paul Goldschmidt, which also has limited Murphy’s playing time when Goldschmidt is the DH, but he has rewarded Leyland’s confidence with a .381 average and no strikeouts in 21 at-bats.