diff --git a/src/client-main.ts b/src/client-main.ts
index cb2cc4328..d47f96db6 100644
--- a/src/client-main.ts
+++ b/src/client-main.ts
@@ -559,6 +559,7 @@ const PS = new class extends PSModel {
 		case 'html':
 		case 'raw':
 		case 'challstr':
+		case 'popup':
 		case '':
 			return [cmd, str.slice(index + 1)];
 		case 'c':
@@ -878,11 +879,18 @@ const PS = new class extends PSModel {
 		}
 		return buf;
 	}
+	getPMRoom(userid: ID) {
+		const myUserid = PS.user.userid;
+		const roomid = `pm-${[userid, myUserid].sort().join('-')}` as RoomID;
+		if (this.rooms[roomid]) return this.rooms[roomid] as ChatRoom;
+		this.join(roomid);
+		return this.rooms[roomid] as ChatRoom;
+	}
 	addRoom(options: RoomOptions, noFocus?: boolean) {
 		// support hardcoded PM room-IDs
 		if (options.id.startsWith('challenge-')) {
 			options.id = `pm-${options.id.slice(10)}` as RoomID;
-			options.challenging = true;
+			options.challengeMenuOpen = true;
 		}
 		if (options.id.startsWith('pm-') && options.id.indexOf('-', 3) < 0) {
 			const userid1 = PS.user.userid;
@@ -902,7 +910,7 @@ const PS = new class extends PSModel {
 				}
 			}
 			if (!noFocus) {
-				if (options.challenging) {
+				if (options.challengeMenuOpen) {
 					(this.rooms[options.id] as ChatRoom).openChallenge();
 				}
 				this.focusRoom(options.id);
diff --git a/src/panel-chat.tsx b/src/panel-chat.tsx
index 9aa985b73..91c2834a9 100644
--- a/src/panel-chat.tsx
+++ b/src/panel-chat.tsx
@@ -9,12 +9,17 @@ class ChatRoom extends PSRoom {
 	readonly classType: string = 'chat';
 	users: {[userid: string]: string} = {};
 	userCount = 0;
+
+	// PM-only properties
 	pmTarget: string | null = null;
-	challenging = false;
+	challengeMenuOpen = false;
+	challengingFormat: string | null = null;
+	challengedFormat: string | null = null;
+
 	constructor(options: RoomOptions) {
 		super(options);
 		if (options.pmTarget) this.pmTarget = options.pmTarget as string;
-		if (options.challenging) this.challenging = true;
+		if (options.challengeMenuOpen) this.challengeMenuOpen = true;
 		this.updateTarget(true);
 		this.connect();
 	}
@@ -64,6 +69,9 @@ class ChatRoom extends PSRoom {
 			}
 			this.openChallenge();
 			return true;
+		} case 'cchall': case 'cancelchallenge': {
+			this.cancelChallenge();
+			return true;
 		}}
 		return false;
 	}
@@ -72,7 +80,21 @@ class ChatRoom extends PSRoom {
 			this.receive(`|error|Can only be used in a PM.`);
 			return;
 		}
-		this.challenging = true;
+		this.challengeMenuOpen = true;
+		this.update('');
+	}
+	cancelChallenge() {
+		if (!this.pmTarget) {
+			this.receive(`|error|Can only be used in a PM.`);
+			return;
+		}
+		if (this.challengingFormat) {
+			this.send('/cancelchallenge', true);
+			this.challengingFormat = null;
+			this.challengeMenuOpen = true;
+		} else {
+			this.challengeMenuOpen = false;
+		}
 		this.update('');
 	}
 	send(line: string, direct?: boolean) {
@@ -310,30 +332,57 @@ class ChatPanel extends PSRoomPanel<ChatRoom> {
 	challenge = (e: Event, format: string, team?: Team) => {
 		const room = this.props.room;
 		const packedTeam = team ? team.packedTeam : '';
-		room.challenging = false;
 		if (!room.pmTarget) throw new Error("Not a PM room");
 		PS.send(`|/utm ${packedTeam}`);
 		PS.send(`|/challenge ${room.pmTarget}, ${format}`);
+		room.challengeMenuOpen = false;
+		room.challengingFormat = format;
+		room.update('');
+	};
+	acceptChallenge = (e: Event, format: string, team?: Team) => {
+		const room = this.props.room;
+		const packedTeam = team ? team.packedTeam : '';
+		if (!room.pmTarget) throw new Error("Not a PM room");
+		PS.send(`|/utm ${packedTeam}`);
+		this.props.room.send(`/accept`);
+		room.challengedFormat = null;
+		room.update('');
 	};
 	cancelChallenge = (e: Event) => {
+		e.preventDefault();
+		e.stopImmediatePropagation();
+		this.props.room.cancelChallenge();
+	};
+	rejectChallenge = (e: Event) => {
 		const room = this.props.room;
-		room.challenging = false;
-		room.update('');
+		room.challengedFormat = null;
+		room.send(`/reject`);
 	};
 	render() {
 		const room = this.props.room;
 
-		const challenge = room.challenging ? <div class="challenge">
+		const challengeTo = room.challengingFormat ? <div class="challenge">
+			<TeamForm format={room.challengingFormat} onSubmit={null}>
+				<button onClick={this.cancelChallenge} class="button">Cancel</button>
+			</TeamForm>
+		</div> : room.challengeMenuOpen ? <div class="challenge">
 			<TeamForm onSubmit={this.challenge}>
 				<button type="submit" class="button disabled"><strong>Challenge</strong></button> {}
 				<button onClick={this.cancelChallenge} class="button">Cancel</button>
 			</TeamForm>
 		</div> : null;
 
+		const challengeFrom = room.challengedFormat ? <div class="challenge">
+			<TeamForm format={room.challengedFormat} onSubmit={this.acceptChallenge}>
+				<button type="submit" class="button disabled"><strong>Accept</strong></button> {}
+				<button onClick={this.rejectChallenge} class="button">Reject</button>
+			</TeamForm>
+		</div> : null;
+
 		return <PSPanelWrapper room={this.props.room}>
 			<div class="tournament-wrapper hasuserlist"></div>
 			<ChatLog class="chat-log hasuserlist" room={this.props.room} onClick={this.focusIfNoSelection}>
-				{challenge}
+				{challengeTo || challengeFrom && [challengeTo, challengeFrom]}
 			</ChatLog>
 			<ChatTextEntry room={this.props.room} onMessage={this.send} onKey={this.onKey} />
 			<ChatUserList room={this.props.room} />
diff --git a/src/panel-mainmenu.tsx b/src/panel-mainmenu.tsx
index b25452476..4485702c7 100644
--- a/src/panel-mainmenu.tsx
+++ b/src/panel-mainmenu.tsx
@@ -38,6 +38,9 @@ class MainMenuRoom extends PSRoom {
 		case 'updateuser':
 			PS.user.setName(tokens[1], tokens[2] === '1', tokens[3]);
 			return;
+		case 'updatechallenges':
+			this.receiveChallenges(tokens[1]);
+			return;
 		case 'queryresponse':
 			this.handleQueryResponse(tokens[1] as ID, JSON.parse(tokens[2]));
 			return;
@@ -47,10 +50,37 @@ class MainMenuRoom extends PSRoom {
 		case 'formats':
 			this.parseFormats(tokens);
 			return;
+		case 'popup':
+			alert(tokens[1]);
+			return;
 		}
 		const lobby = PS.rooms['lobby'];
 		if (lobby) lobby.receive(line);
 	}
+	receiveChallenges(dataBuf: string) {
+		let json;
+		try {
+			json = JSON.parse(dataBuf);
+		} catch {}
+		for (const userid in json.challengesFrom) {
+			PS.getPMRoom(toID(userid));
+		}
+		if (json.challengeTo) {
+			PS.getPMRoom(toID(json.challengeTo.to));
+		}
+		for (const roomid in PS.rooms) {
+			const room = PS.rooms[roomid] as ChatRoom;
+			if (!room.pmTarget) continue;
+			const targetUserid = toID(room.pmTarget);
+			if (!room.challengedFormat && !(targetUserid in json.challengesFrom) &&
+				!room.challengingFormat && (json.challengeTo || {}).to !== targetUserid) {
+				continue;
+			}
+			room.challengedFormat = json.challengesFrom[targetUserid] || null;
+			room.challengingFormat = json.challengeTo.to === targetUserid ? json.challengeTo.format : null;
+			room.update('');
+		}
+	}
 	parseFormats(formatsList: string[]) {
 		let isSection = false;
 		let section = '';
@@ -378,7 +408,7 @@ class TeamDropdown extends preact.Component<{format: string}> {
 
 class TeamForm extends preact.Component<{
 	children: preact.ComponentChildren, class?: string, format?: string,
-	onSubmit: (e: Event, format: string, team?: Team) => void,
+	onSubmit: null | ((e: Event, format: string, team?: Team) => void),
 }> {
 	state = {format: '[Gen 7] Random Battle'};
 	changeFormat = (e: Event) => {
@@ -389,7 +419,7 @@ class TeamForm extends preact.Component<{
 		const format = (this.base!.querySelector('button[name=format]') as HTMLButtonElement).value;
 		const teamKey = (this.base!.querySelector('button[name=team]') as HTMLButtonElement).value;
 		const team = teamKey ? PS.teams.byKey[teamKey] : undefined;
-		this.props.onSubmit(e, format, team);
+		if (this.props.onSubmit) this.props.onSubmit(e, format, team);
 	};
 	render() {
 		return <form class={this.props.class} onSubmit={this.submit}>