Zverev, in search of his third ATP Finals title, adopted up his defeat of Rublev with a straight-set win in opposition to Norwegian sixth seed Ruud.
Ruud solely missed six of his first serves within the first set however Zverev dominated the tie-break after the opening 12 video games yielded no break factors.
With an hour and 20 minutes gone, Zverev lastly secured a break to go 5-3 up within the second set and served out to like for victory.
“I feel it was an excellent match truly from each of us,” he stated. “I am joyful to win right this moment nevertheless it was very, very shut.”
On Thursday, American Taylor Fritz faces Australian Alex de Minuar (13:00 GMT) within the ultimate spherical of Ilie Nastase Group matches.
World primary Jannik Sinner will attain the final 4 if he claims a set in opposition to Daniil Medvedev (19:30), and can high the group with a 3rd straight win.