However, it was arguably Dutchman Tom Dumoulin, who is not recognised for his climbing prowess, who put in the most impressive performance on the third of three consecutive summit finishes as he again avoided losing too much time on his main rivals and is now the clear favourite.
Dumoulin (Giant-Alpecin) is just under two minutes behind Rodriguez in fourth heading into Tuesday's rest day and is expected to surge into the lead after Wednesday's time trial in Burgos, a discipline he excels in.
"That was much better than expected," Dumoulin told reporters.
"I didn't feel so good on the first (category) climb, it went really fast, but I was never really in trouble and I thought 'ah we'll give it a go on the last climb'," he added.
"I had really good legs, to lose (only) 28 seconds is really, really good, still everything is open."
Spaniard Rodriguez (Katusha), who won Sunday's 15th stage to close to within one second of Aru, finished almost nine minutes behind in ninth, trying desperately to put some distance between himself and the Italian who hung on bravely.
Rodriguez finished two seconds ahead of Aru to claim the leader's red jersey.
Trek rider Schleck, whose impressive victory came 45 years after his father Johny won a Vuelta stage in Madrid, was part of a small group that broke away near the start of the 185-kilometre slog from Luarca to Ermita de Alba, which included seven punishing climbs and some eye-watering gradients.
By the time the 35-year-old reached the final ascent after nearly six hours in the saddle, he had dropped all his rivals except Rodolfo Torres (Team Colombia) and he surged away to cross the line one minute and 10 seconds ahead of the Colombian.
"I was very nervous, Torres was tough," said Schleck, who missed the Tour de France with a knee injury.
"I didn't really know much about Torres or what he could do."
Poland's Rafal Majka (Tinkoff-Saxo) is in third overall, just over one and half minutes behind Rodriguez and Aru.
The three-week race ends on Sept. 13 in central Madrid.
(The story was refiled to remove the extraneous word 'said' in eleventh paragraph)
(Reporting by Iain Rogers, editing by Martyn Herman)
