Clark, NCAA Division I basketball's all-time leading scorer, has brought unprecedented attention to women's basketball with her college career which rewrote the record books and shattered attendance and television viewing records.
Indiana took her as the number one draft pick, maintaining the buzz around Clark which had peaked with her run to the national championship game with Iowa.
The hype in the build-up was always going to be hard to live up to, but Clark and her team endured a tough night against a strong Suns defense.
The game at the Mohegan Sun Arena in Uncasville, Connecticut, was sold out, with courtside seats being offered for as much as $4,262 on secondary markets.
While she was making her debut on the road, it was evident from the crowd reactions that many had come just to see the star of last month's NCAA tournament.
Clark's 20 points made her the Fever's top scorer and came on 5-of-15 shooting, 4-of-11 on three-pointers and 6-of-6 on free throws. She also had three assists, two steals and 10 turnovers.
Clark struggled early in the game, picking up two touch fouls which saw her head to the bench prematurely.
Her first points did not come until there was 5:24 remaining in the second quarter, although she found her flow later with 13 second-half points.
The Sun's star forward Alyssa Thomas recorded a triple double with 13 points, 10 rebounds and 13 assists.
Clark will make her home debut in Indianapolis on Thursday against last year's WNBA runner-up New York Liberty.
