Aru's nightmare day began after just 72km, when he was involved in a crash. While it was not a major incident, it clearly rattled the Italian who needed to chase back on in haste.
The Astana rider then lost three seconds on the road to Tom Dumoulin (Giant-Alpecin) after the race leader attacked at the end of Stage 19, putting Aru six seconds behind the Dutchman.
While still a slim margin, the fact that Dumoulin seems to be getting stronger towards the end of the race will be a significant psychological boost for the Giant-Alpecin rider.
However, Aru may have bigger issues after after apparently accepting a handsling from teammate Luis Leon Sanchez. Sanchez seemingly pushed Aru on a cobbled climb at 1.5km to go, as Dumoulin pulled away from the bunch. If the race jury finds Aru guilty, he could receive a time penalty or even be ejected from the race like his erstwhile teammate Vincenzo Nibali.
The race jury has not yet decided whether Aru will be punished after reviewing the footage post-stage, but will review it and additional video evidence before the start of Stage 20.
The stressful day clearly affected Aru, who skipped the podium ceremony and was reportedly quite agitated after the stage.
According to Cycling Weekly's Gregor Brown, Aru was bundled into the Astana team van after shouting at a journalist. To add insult to injury, the driver of the van also scraped it against a railing as they tried to make a swift getaway.
Aru clearly faces a tense night ahead of the decisive Stage 20, especially as he waits to see the outcome of the race jury's inquest into the handsling incident.