diff --git a/backend/siarnaq/bracket/challonge.py b/backend/siarnaq/bracket/challonge.py
index 2c81b6e74..5e39bedcb 100644
--- a/backend/siarnaq/bracket/challonge.py
+++ b/backend/siarnaq/bracket/challonge.py
@@ -7,12 +7,13 @@
 from django.apps import apps
 from django.conf import settings
 
+from siarnaq.api.teams.models import Team
+
 if TYPE_CHECKING:
     from typing import Iterable
 
     from siarnaq.api.compete.models import Match, MatchParticipant
     from siarnaq.api.episodes.models import Tournament, TournamentRound
-    from siarnaq.api.teams.models import Team
 
 
 _headers = {
@@ -24,8 +25,7 @@
     "User-Agent": "",
 }
 
-AUTH_TYPE = "v1"
-URL_BASE = "https://api.challonge.com/v2/"
+URL_BASE = "https://api.challonge.com/v2.1/"
 
 
 def create_tournament(tournament: Tournament, *, is_private: bool):
@@ -84,16 +84,14 @@ def bulk_add_teams(tournament: Tournament, teams: Iterable[Team], *, is_private:
         {
             "name": team.name,
             "seed": idx + 1,
-            "misc": json.dumps(
-                {"team_id": team.id, "submission_id": team.active_submission}
-            ),
+            "misc": json.dumps({"team_id": team.id}),
         }
         for (idx, team) in enumerate(teams)
     ]
 
     payload = {
         "data": {
-            "type": "Participant",
+            "type": "Participants",
             "attributes": {
                 "participants": participants_for_challonge,
             },
@@ -138,7 +136,7 @@ def get_tournament_data(tournament: Tournament, *, is_private: bool):
         # in case of bracket reset
         matches = [item for item in data["included"] if item["type"] == "match"]
         match_last = max(
-            matches, key=lambda match: match["attributes"]["suggestedPlayOrder"]
+            matches, key=lambda match: match["attributes"]["suggested_play_order"]
         )
         # Give it its own round
         match_last["attributes"]["round"] += 1
@@ -156,7 +154,7 @@ def _get_round_indexes(tournament: Tournament, *, is_private: bool):
     round_indexes = list()
 
     matches = [item for item in tournament_data["included"] if item["type"] == "match"]
-    matches.sort(key=lambda i: i["attributes"]["suggestedPlayOrder"])
+    matches.sort(key=lambda i: i["attributes"]["suggested_play_order"])
 
     for match in matches:
         round_index = match["attributes"]["round"]
@@ -271,6 +269,14 @@ def get_match_and_participant_objects_for_round(round: TournamentRound):
     # and map them with IDs for easy lookup
     challonge_participants = dict()
 
+    # Hold a map of all teams' latest submission for the tournament,
+    # for quick simple lookups later
+    team_submissions = dict(
+        Team.objects.with_active_submission()
+        .values_list("pk", "active_submission")
+        .all()
+    )
+
     for item in tournament_data_private["included"]:
         match item:
             case {
@@ -322,15 +328,12 @@ def get_match_and_participant_objects_for_round(round: TournamentRound):
         )
         match_objects.append(match_object)
 
-        # Note that Challonge 1-indexes its player indexes
-        # while our internal data model (in Siarnaq) 0-indexes.
-        for (siarnaq_player_index, challonge_player_index) in enumerate(
-            ["player1", "player2"]
-        ):
+        challonge_points = challonge_match["attributes"]["points_by_participant"]
+        for (player_index, challonge_points_participant) in enumerate(challonge_points):
             # This looks ugly but it's how to parse through the Challonge-related data.
-            challonge_participant_id_private = challonge_match["relationships"][
-                challonge_player_index
-            ]["data"]["id"]
+            challonge_participant_id_private = str(
+                challonge_points_participant["participant_id"]
+            )
             challonge_participant_id_public = challonge_team_ids_private_to_public[
                 challonge_participant_id_private
             ]
@@ -340,13 +343,13 @@ def get_match_and_participant_objects_for_round(round: TournamentRound):
                 ]
             )
             team_id = misc_key["team_id"]
-            submission_id = misc_key["submission_id"]
+            submission_id = team_submissions[team_id]
 
             match_participant_object = apps.get_model("compete", "MatchParticipant")(
                 team_id=team_id,
                 submission_id=submission_id,
                 match=match_object,
-                player_index=siarnaq_player_index,
+                player_index=player_index,
                 external_id_private=challonge_participant_id_private,
                 external_id_public=challonge_participant_id_public,
             )
@@ -393,7 +396,7 @@ def update_match(match: Match, *, is_private: bool):
             if is_private
             else participant.external_id_public,
             "score_set": str(participant.score),
-            "advancing": True if participant.score == high_score else False,
+            "advancing": participant.score == high_score,
         }
         for participant in participants
     ]