Bormio - Giro d'Italia leader Tom Dumoulin suffered a "terrible" day but refused to blame his rivals for capitalising on an unscheduled toilet stop that badly hurt his overall victory hopes on Tuesday.
The Sunweb team rider started the "Queen" mountain stage of the 100th edition with a lead of 2:41 on Colombian climbing specialist and 2014 champion Nairo Quintana (Movistar), and with high hopes of becoming the first Dutchman to win the pink jersey.
But by the end of the 222 km ride from Rovetta to Bormio - won by Italy's Vincenzo Nibali (Bahrain team) - Dumoulin's dream was shattered after seeing his lead over Quintana slashed to 31 seconds.
There were some suggestions his rivals had shown poor sportsmanship, attacking while he made a desperate toilet stop following the first of two ascensions of the Stelvio climb.
"I don't know, it's difficult to say," said Dumoulin, when asked if he was angry.
In professional cycling rivals often wait for each other following unexpected incidents to ensure a fair battle.
On Sunday, Movistar leader Quintana thanked Dumoulin for slowing the pace of the peloton when he crashed so he could catch up.
In contrast, no teams slowed when Dumoulin suffered his mishap, the Dutchman forced to hurriedly throw his bike into the grass and rip off his cycling shorts in desperation as he suffered a bout of diarrhea.
"It was a race situation, we were going full gas and I didn't expect them to stop," added Dumoulin.
In the end, he battled on the second ascension of the Stelvio to crest the snow-hit summit 2:06 behind Quintana and Nibali, and continued his valiant effort on the sinewy downhill to come over the line 2:17 in arrears after Nibali beat Spanish rival Mikel Landa (Sky) in a two-up sprint to end the hosts' long wait for a stage win on the 100th edition.
With another four mountain stages still to come, time-trial specialist Dumoulin was left despondent.
"I'm still in (the leader's jersey) but not with the lead I had hoped for," a dejected-looking Dumoulin said at the finish.
"I'm disappointed with myself. I lost two minutes not because I had bad legs, just because I had other problems.
"It was terrible. I had to stop because I couldn't hold it anymore.
"I had to fight and fight and fight, and take conclusions after the finish. That’s what I did. I'm very disappointed with today."
Nibali, who suggested Dumoulin had "not been feeding right" or perhaps suffered a chill due to the "cold temperatures", had little sympathy for the Dutchman.
"It wasn't a crash," said Nibali when asked if he and the peloton had thought to stop and wait.
"No one has ever stopped and waited for me whenever I've ever had a problem, and I've had plenty in the past whether it's being sick, a crash or a flat tire.
"Maybe I'll be attacked for what I say but if you look at the history of cycling, there are plenty of incidents of riders attacking their rivals in such circumstances."
Now in third place overall at 1:12 behind Dumoulin, Nibali is back in with a fighting chance of winning his home race on its 100th edition.
But after the hosts waited 16 stages to celebrate a home win, he said: "Climbing the Mortirolo and the Stelvio - the highest peak on this year's race - twice? This is a great stage win for me.
"The only regret I have is not putting my hands up at the finish to celebrate. But I was too busy sprinting."
Results from the 16th stage of the Giro d'Italia, held over 222km between Rovetta and Bormio on Tuesday:
1. Vincenzo Nibali (ITA/BAH) 6hr 24min 22sec, 2. Mikel Landa (ESP/SKY) same time, 3. Nairo Quintana (COL/MOV) at 12sec, 4. Domenico Pozzovivo (ITA/ALM) 0:24, 5. Ilnur Zakarin (RUS/KAT) 0:32, 6. Davide Formolo (ITA/CAN) 1:26, 7. Bauke Mollema (NED/TRE) 1:35, 8. Bob Jungels (LUX/QST) s.t., 9. Adam Yates (GBR/ORI) s.t., 10. Thibaut Pinot (FRA/FDJ) s.t.
Selected: 12. Steven Kruijswijk (NED/TLJ) s.t., 13. Tom Dumoulin (NED/SUN) 2:18
1. Tom Dumoulin (NED/SUN) 70hr 14min 48sec, 2. Nairo Quintana (COL/MOV) at 31sec, 3. Vincenzo Nibali (ITA/BAH) 1:12, 4. Thibaut Pinot (FRA/FDJ) 2:38, 5. Ilnur Zakarin (RUS/KAT) 2:40, 6. Domenico Pozzovivo (ITA/ALM) 3:05, 7. Bauke Mollema (NED/TRE) 3:49, 8. Bob Jungels (LUX/QST) 4:35, 9. Steven Kruijswijk (NED/TLJ) 6:20, 10. Adam Yates (GBR/ORI) 7:00