Gazprom Rus Velo's Alexander Foliforov took the win on stage fifteen of the 99th Giro D'Italia.
Stage 15 was another time trial and this one in the mountains, was 10.8kms long and from Castelrotto to Alpe di Siusi with plenty of climbing in the latter stages.
Giant Alpecin's Cheng Ji set the early fastest time of 33.13 before Boswell took over as the leader.
Alexander Foliforov of Gazprom-Rusvelo was fastest through the first check after 4.4kms and he kept going to take over the lead with a time of 28:39.
That was still the best time when race leader Steven Kruijswijk went down the ramp and with Vincenzo Nibali losing time due to a mechanical.
Steven Kruijswijk finished second to put more time into his rivals and give the delighted Russian the win and Steven Kruijswijk now leads the race by 2.26 going into the final week.