Porte finished just 0:58 of a second behind Tom Dumoulin (57:16:30) - the fastest rider at the finish on Stage 20 - before Tadej Pogačar smashed everyone out of the water, ripping the yellow jersey off Primož Roglič's back with a time of 55:55.
The Australian produced a blistering ride in the individual time trial - the third fastest of the day - and was 35 seconds quicker than previous general classification leader Primož Roglič.
Fellow Aussie cycling star Caleb Ewan, along with triple Tour de France green jersey winner and SBS commentator, Robbie McEwen were among those to congratulate 35-year-old Porte.
"Big congrats Richie Porte, on the podium! What a ride!" Ewan said via Twitter, with McEwen responding to Porte's Instagram post to pass on his own congratulations.
Two-time Olympic gold medallist Anna Meares was also quick to congratulate Porte via social media.
Meanwhile, two-time AFL premiership winner Riewoldt commented on Porte's Instagram post, labelling him the "king of Tassie."
Likwise, Siddle - who represented the Australian cricket team on 89 occasions before retiring last year - also continued his support of Porte.
"Now that’s a ride mate. Congrats!" Siddle said via Instagram.