Luigi Riva, the all-time leading goalscorer for Italy's men's national team -- known as the "Rombo di Tuono" (Rumble of Thunder) -- has died. He was 79.

The Italian soccer federation (FIGC) confirmed Riva died on Monday as tributes started flooding in for the player, who earned his nickname because of the potency of his shot with 35 goals in 42 appearances for Italy.

"I'm shaken and profoundly saddened, Italian soccer is grieving because a real and proper national hero has left us," FIGC President Gabriele Gravina said. "Gigi Riva was the embodiment of a great man and an extraordinary footballer: his pride, his class and his sense of fairness united generations.

"Thanks to him we won the European Championship in 1968 and the World Cup in 2006 [as team manager]."

Riva was taken to the cardiology unit at Brotzu Hospital on Sunday after collapsing at home and the Cagliari hospital issued a statement on Monday evening saying his condition had improved. But he died shortly afterward.

"He had a serious coronary heart disease," doctors at the hospital said in quotes reported by Gazzetta dello Sport. "This morning specialists recommended an angioplasty surgery. He decided to think about it. Nothing made us think he would worsen suddenly.

"He had been informed of the risk of death ... he seemed serene and good-tempered, very calm. He was in agreement with the statement on how he was doing, knowing that the city and the nation wished him well."

Riva spent almost his entire career at Cagliari after joining the Sardinian team as a teenager, refusing several lucrative offers to join other clubs -- especially when he was at the top of his game and Cagliari was struggling.

He helped Cagliari to their only Serie A title in 1970 and remains the club's record scorer, with 205 goals in 374 matches.

Several Italian clubs posted messages of condolences on social media. Cagliari simply wrote: "For ever GIGI RIVA" above a large photo of the player. They also added a black ribbon to their social media profiles.

As a player, he helped the Azzurri win the European Championship in 1968 and finish runners-up at the World Cup two years later.

He was also team manager of the national side from 1990-2013 and was instrumental in Italy winning a fourth World Cup in 2006.

A minute's silence will be held before the start of all soccer matches in Italy this weekend in tribute to Riva, while there was also a minute's silence before the start of the second half of the Italian Super Cup final that was taking place in Riyadh, Saudi Arabia on Monday.