Short answers, pulled from the story.
Matthäus appeared at five FIFA World Cups (1982, 1986, 1990, 1994, and 1998), making him the first outfield player and second player overall, after Mexican goalkeeper Antonio Carbajal, to achieve that feat. His total of 25 World Cup appearances was a record at the time of his retirement, since surpassed by Lionel Messi.
Matthäus won the FIFA World Player of the Year award in 1991, making him the first-ever recipient of the honour. He remains the only German player to have received the award.
Matthäus played professionally for Borussia Mönchengladbach (1979-1984), Bayern Munich (1984-1988 and 1992-2000), Inter Milan (1988-1992), and the MetroStars in Major League Soccer (2000). He also made a brief comeback appearance for 1. FC Herzogenaurach in 2018.
Maradona called Matthäus "the best rival I've ever had," adding "I guess that's enough to define him." The two faced each other in the 1986 and 1990 World Cup finals, with Matthäus assigned to mark Maradona personally in 1986.
Matthäus earned 150 international caps in total across 20 years, with 83 appearances for West Germany before reunification. He scored 23 international goals and remains the most capped German player of all time.
Matthäus managed SK Rapid Wien (2001-2002), FK Partizan (2002-2003), the Hungary national team (2003-2006), Athletico Paranaense (January-March 2006), Red Bull Salzburg (2006-2007), Maccabi Netanya (2008-2009), and the Bulgaria national team (2010-2011). His most notable coaching achievement was guiding Partizan to the 2002-03 Serbian SuperLiga title and to the UEFA Champions League group stage.