The math worked this season, sending the quartet of teams that proved most efficient until now all the way to the Turkish Airlines EuroLeague Final Four in Belgrade. Here's what to watch out for when they match up in the semis.
Stats Review: Sizing up the semis

Final Four Reset
FC Barcelona and Olympiacos Piraeus both earned hard-fought wins in the decisive fifth games of their respective quarterfinal series to join Real Madrid and Anadolu Efes Istanbul in the Turkish Airlines EuroLeague Final Four.

Those four teams had the league's highest efficiency differentials, making this season an instance where the numbers matched reality. However, if history is any indicator, what happens from here is more complicated. Just two of the last five teams to raise the trophy have held the league's highest efficiency differential.
Semifinal B: Efes vs. Olympiacos
The reigning champions have looked the part after a sluggish start to the season and defended better than expected in their quarterfinal victory of AX Armani Exchange Milan. While they split their regular season series with Olympiacos, they averaged 1.10 points per possession in those matchups thanks in large part to a stellar shooting effort from Rodrigue Beaubois in their Round 10 victory.
Olympiacos is looking to make its first championship game appearance since a stretch where they went 2-2 in finals across six seasons starting back in 2011. As usual, the Reds were dominant at home this season, but fought through considerable adversity to beat Monaco who handed them one of their bigger home losses in recent memory in the quarterfinals. The rise of Sasha Vezenkov has been a bright spot among many in a bounce-back year for the historic franchise, but it was Kostas Sloukas and Tyler Dorsey who delivered in their win over Efes in Round 26.
What to watch: Ball Screens
Olympiacos and Efes ranked first and second in the EuroLeague by creating 48% and 45% of their half-court possessions, respectively, out of pick-and-rolls this season. They also ranked in the top four in efficiency in both ball-screen and overall efficiency. In regular season matchups with Olympiacos, Efes aggressively looked to Vasilije Micic and Shane Larkin to attack individual matchups on the perimeter, so guard play figures to be at a premium in this matchup. Which team's shooters deliver and which big men step up when guarding the two-man game will also factor heavily into how this season's two most prolific pick-and-roll offenses fare.
Semifinal A: Barcelona vs. Real
Barca has beaten Real five straight times this season after dropping their first matchup in the preseason Supercup nearly nine months ago. Barca will need to extend that streak to six to earn a chance to redeem their finals loss a year ago. In their two EuroLeague wins, Barcelona pivoted from playing through the post to a more pick-and-roll-centric attack. Nikola Mirotic and Nicolas Laprovittola were the heroes in those wins. Laprovittola was also critical to Barcelona's Game 5 win over FC Bayern Munich in what was a grueling quarterfinal series for this year's top seed.
Real, in contrast, made quick work of Maccabi Playtika Tel Aviv, winning all three of their quarterfinal games by double-digits with Sergio Llull catching fire. They have hung their hat on the defensive end all season but will need someone to step up on the offensive end to reverse their fortunes against Barcelona. Llull struggled against Barcelona in the regular season, making his recent resurgence a point of interest in the Final Four. Walter Tavares's foul situation is also something to monitor as he was a bright spot in Real's pair of losses to Barca amid foul trouble.
What to Watch: Catch-and-Shoot Jumpers
No teams made catch and shoot jump shots more consistently than Barca and Real, who ranked first and second in the EuroLeague, shooting eFG%s of 58% and 59%, respectively. Real only attempted 9.5 catch-and-shoot jumpers per game within their set offense in their two EuroLeague losses to Barca – well below their 18.1 per-game season standard. How steadily they can create clean looks on the perimeter figures to be their x-factor in this game.