diff --git a/src/Tiebreaks.php b/src/Tiebreaks.php
index f5a1e0c..1670315 100644
--- a/src/Tiebreaks.php
+++ b/src/Tiebreaks.php
@@ -9,10 +9,10 @@ use JeroenED\Libpairtwo\Enums\Result;
 
 abstract class Tiebreaks extends Tournament
 {
-
     private const Won = [ Result::won, Result::wonforfait, Result::wonbye, Result::wonadjourned ];
     private const Draw = [ Result::draw, Result::drawadjourned];
     private const Lost = [ Result::absent, Result::bye, Result::lost, Result::adjourned ];
+    private const NotPlayed = [ Result::bye, Result::wonbye, Result::absent ];
     private const Black = [ Color::black ];
     private const White = [ Color::white ];
 
@@ -137,12 +137,24 @@ abstract class Tiebreaks extends Tournament
         return $points;
     }
 
-    protected function calculateAverageRating(Player $player) {
+    /**
+     * @param Player $player
+     * @return float
+     */
+    protected function calculateAverageRating(Player $player)
+    {
         $pairings = $player->getPairings();
         $totalrating = 0;
-        $opponents;
+        $totalopponents = 0;
         foreach ($pairings as $pairing) {
-            if ($pairing->getOpponent()->getElos['national'])
+            if (array_search($pairing->getResult(), self::NotPlayed) === false) {
+                $toadd = $pairing->getOpponent()->getElos()['home'];
+                if ($toadd != 0) {
+                    $totalrating += $toadd;
+                    $totalopponents++;
+                }
+            }
         }
+        return round($totalrating / $totalopponents);
     }
 }
diff --git a/src/Tournament.php b/src/Tournament.php
index b106839..6968a6c 100644
--- a/src/Tournament.php
+++ b/src/Tournament.php
@@ -290,6 +290,9 @@ class Tournament extends Tiebreaks
             case Tiebreak::Between:
                 return $this->calculateMutualResult($player, $this->getPlayers(), $tbkey);
                 break;
+            case Tiebreak::Aro:
+                return $this->calculateAverageRating($player);
+                break;
             default:
                 return null;
         }