The "BVB" controlled possession and should have added another goal to its lead before the break but Freiburg's goalkeeper Florian Muller was on guard to defuse the efforts from Thomas Meunier and Mats Hummels in the closing period of the first half.
"In the second set and the third set, I had a lot of opportunities, also easy opportunities," said Schwartzman after his 20th victory of 2020. "That's why I was really upset, really angry with myself at that time ... when I was close to winning in those sets. I couldn't do it."
Elsewhere, Wolfsburg and Augsburg shared the spoils after playing out a goalless stalemate. Enditem
The 2018 champion lost to Anisimova in the quarterfinals in Paris last year, but this time the Romanian needed only 54 minutes to complete a convincing victory.
"They're the best team in the league, and proved it today," said Shandong coach Luka Sjekloca. Enditem
"We aimed at testing the team, as the two sides have a big gap. Our players executed our tactics in transition, but we made too many mistakes," rued Hebei coach Ma Tao.
But Wu was reluctant to highlight her own performance.
"I executed the race well despite not being fully fit. I have a hamstring injury that I want to manage when I take a break, this being the last event this season. It feels good to end the season on a winning tone, especially at home, having won the Diamond League races in Monaco and Stockholm.
"We heated up quickly into the game, but failed to do enough on defence and rebounds," said Han.
"To be honest I was over the limit today. At the end I gave everything that I had out there, it was an amazing match," the 27-year-old added.
The stadium has a total area of more than 107,000 square meters, including 18,000 seats and an ice rink of 1,800 square meters, which is the largest ice rink in northwest China.