San Antonio Spurs legend Tim Duncan is calling it a career after 19 seasons and five NBA championships.Duncan's announcement Monday marks the end of an era for the Spurs. The 6-foot-11 power forward superstar also won two MVP awards, was a three-time NBA Finals MVP, made 15 All-Star appearances and was named to the All-NBA First Team 10 times in his career. He also made the NBA All-Defensive First Team eight times."Tim Duncan is one of the most dominant players in NBA history. His devotion to excellence and mastery of the game led to five NBA championships, two regular-season MVP awards and a place among the all-time greats, while his understated selflessness made him the ultimate teammate," NBA commissioner Adam Silver said. "For two decades Tim represented the Spurs, the city of San Antonio and the league with passion and class. All of us in the NBA family thank him for his profound impact on the game."Duncan, who turned 40 in April, was the No. 1 overall pick out of Wake Forest in 1997.Duncan, teaming with head coach Gregg Popovich and Tony Parker and Manu Ginobili, was the backbone for the franchise's championship run.Ginobili wrote on Twitter: "Even tho I knew it was coming, I'm still moved by the news. What a HUGE honor to have played with him for 14 seasons! #ThankYouTD."The Spurs tweeted: "#ThankYouTD, for everything."Duncan spent his entire career with the Spurs, leading the team to titles in 1999, 2003, 2006, 2007 and 2014.The Spurs posted a 1,072-438 regular-season record since drafting Duncan -- the best 19-year stretch in NBA history."More cutthroat than people give him credit for," Los Angeles Lakers legend Kobe Bryant, who also retired after the 2015-16 season, told ESPN's Marc Stein on Monday upon learning of Duncan's retirement. "I loved everything about him on the court."Shaquille O'Neal told ESPN: "Greatest power forward of all time. Unbreakable power forward. No 'bow could break him. No loss of a championship could break him. Nothing could break him."Duncan's final game was a 113-99 loss to the Oklahoma City Thunder in Game 6 of the Western Conference semifinals on May 12. In his career finale, he scored 19 points, with five rebounds and a block in 34 minutes.Duncan finished his career with averages of 19.0 points, 10.8 rebounds, 3.0 assists and 2.2 blocks per game. He ranks 14th all-time in points (26,496), sixth in rebounds (15,091) and fifth in blocks (3,020).Last season, Duncan was hobbled by a sore right knee and played in only 61 games, averaging 8.6 points and 7.3 rebounds.Popovich will discuss Duncan's retirement decision at a news conference Tuesday. Duncan and Popovich have the most wins by a player-coach duo in NBA history (1,001)."Timmy's never been a very outspoken or emoting sort of individual on the court," Popovich said earlier this year. "Everybody does it differently."Golden State Warriors coach Steve Kerr, who played with Duncan for four seasons, said it will not be the same without Duncan on the court."When you think of a Spurs game, you think of the opening tip and Timmy cradling the ball and looking down at Pop and Manu and Tony," Kerr told ESPN. "The four of them really kind of define who they are. But Tim is the main guy obviously."They'll still be the Spurs based on what they've built. And maybe that's Timmy's lasting legacy. He helped build something so strong that's still going after he leaves."