Caitlin Clark believes she is only "scratching the surface" after the Indiana Fever lost 87-81 to Connecticut Sun to end her hopes of finishing her rookie year with a WNBA Championship title.

In the season-ending loss to the Sun, Clark scored 25 points, adding nine assists and six rebounds, becoming the first rookie to have pulled off a 25-5-5 game in the postseason.

However, she was powerless to stop the Sun from clinching the best-of-three contest 2-0, despite the Fever leading the contest in the final quarter.

But led by 19 points and 13 assists from Alyssa Thomas, Connecticut retook the lead late on to seal their progression to the semi-finals.

Clark set regular-season records throughout the year for assists (337), points by a rookie (769) and three-pointers by a rookie (122) in her debut campaign.

Despite the season ending in disappointment, Clark has vowed to return even stronger next season.

"The fun part is I feel like I'm just scratching the surface, and I'm one that's nit-picking every single thing I do," said Clark.

"I know I want to help this franchise get even better, help my team-mates get even better, and I know there's a lot of room for me to continue to improve.

"I feel like I could continue to get a lot better, and before we know it, I'm sure we'll all be back here and ready for the next year."

The Sun will face the Minnesota Lynx in the play-off semi-finals while Clark will begin her off-season.