diff --git a/src/elo.rs b/src/elo.rs
index 78d8bb0..a17350e 100644
--- a/src/elo.rs
+++ b/src/elo.rs
@@ -5,6 +5,7 @@ use crate::{
     logic::FutureMoveConfig,
     repr::{Piece, Winner},
 };
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use skillratings::{
     elo::{elo, EloConfig, EloRating},
     Outcomes, Rating,
@@ -114,14 +115,28 @@ impl PlayerArena {
         }
     }
 
-    fn play_all_against(&mut self, i: usize) {
-        for j in 0..self.players.len() {
-            if i == j {
-                continue;
-            }
+    fn play(&mut self, pairs: &[(usize, usize)]) {
+        pairs
+            .iter()
+            .map(|&(i, j)| {
+                (
+                    (i, j),
+                    Self::create_agents(&self.players[i].1, &self.players[j].1),
+                )
+            })
+            .map(|((i, j), (p1, p2))| (i, j, Self::play_two_inner(p1, p2)))
+            .collect::<Vec<_>>()
+            .into_iter()
+            .for_each(|(i, j, o)| self.process_outcome(i, j, &o));
+    }
 
-            self.play_two(i, j);
-        }
+    fn play_all_against(&mut self, i: usize) {
+        self.play(
+            &(0..self.players.len())
+                .zip([i].into_iter().cycle())
+                .filter(|(i, j)| i != j)
+                .collect::<Vec<_>>(),
+        )
     }
 
     fn prop_arena(&mut self) {
@@ -130,30 +145,38 @@ impl PlayerArena {
         }
     }
 
-    fn play_two(&mut self, player1: usize, player2: usize) {
-        println!(
-            "{} vs {}...",
-            self.players[player1].0, self.players[player2].0
-        );
-
-        let outcome = Self::play_two_inner(&self.players[player1].1, &self.players[player2].1);
-
+    fn process_outcome(&mut self, player1: usize, player2: usize, outcome: &Outcomes) {
         let (np1, np2) = elo(
             &self.players[player1].2,
             &self.players[player2].2,
-            &outcome,
+            outcome,
             &EloConfig::new(),
         );
         self.players[player1].2 = np1;
         self.players[player2].2 = np2;
     }
 
-    fn play_two_inner(
+    fn play_two(&mut self, player1: usize, player2: usize) {
+        println!(
+            "{} vs {}...",
+            self.players[player1].0, self.players[player2].0
+        );
+
+        let (p1, p2) = Self::create_agents(&self.players[player1].1, &self.players[player2].1);
+
+        let outcome = Self::play_two_inner(p1, p2);
+        self.process_outcome(player1, player2, &outcome);
+    }
+
+    fn create_agents(
         player_1_fn: &Box<dyn Fn(Piece) -> Box<dyn Agent>>,
         player_2_fn: &Box<dyn Fn(Piece) -> Box<dyn Agent>>,
-    ) -> Outcomes {
-        let result = GameInner::new(player_1_fn(Piece::Black), player_2_fn(Piece::White), false)
-            .loop_until_result();
+    ) -> (Box<dyn Agent>, Box<dyn Agent>) {
+        (player_1_fn(Piece::Black), player_2_fn(Piece::White))
+    }
+
+    fn play_two_inner(player_1: Box<dyn Agent>, player_2: Box<dyn Agent>) -> Outcomes {
+        let result = GameInner::new(player_1, player_2, false).loop_until_result();
 
         match result {
             Winner::Player(piece) => match piece {