Yuki was cruising at one stage but a right ankle problem in the third set hampered his progress. However, he battled out pain and his sluggish rival for a 6-2 6-4 6-7 (1) 6-3 win in two hours and 52 minutes.
Now, Somdev will lock horns with Ti Chen in the second singles rubber.
The battle between the two former junior world number one players was turning out to be quite comfortable for the Indian but Yuki's injury in the ninth game of the third set almost scuttled the home team's chances in the opening rubber of the first round.
To his credit, Yuki did not give up and kept fighting and his persistence finally paid.
At the start, Yuki started dominating the contest with stupendous control over his shots. He kept the ball in and targeted the lines for winners.
Yang started to struggle after a disputed call in the fifth game, when he was facing two break points, disturbed his rhythm.