Champions League Matchday One: Four things to watch

The Champions League is back this week as Europe's elite begin their pursuit of club football's biggest prize.

Matchday one brings blockbuster reunions, unwanted records and plenty of questions for some of the continent's biggest clubs.Jose Mourinho faces former side Inter Milan with history in his sights, while Barcelona must address familiar defensive concerns, and Manchester United will celebrate a major milestone on their return to the competition.