BOSTON -- Boston Celtics point guard Rajon Rondo missed two free throws in a tie game with 64 seconds to play in Friday's 109-102 loss to the Chicago Bulls.

Rondo, a career 61.6 percent free-throw shooter, is now shooting a career-worst 32.1 percent at the line this season. He's 9 of 28 and unsure of why he's struggling so badly.

"It's very frustrating, in particular this game," Rondo said. "If I make my free throws, I think we win the game."

Rondo hit side iron on his first late-game attempt, then found back iron on the other. Boston made a season-high 22 freebies during Friday's game, but missed seven attempts, with Jared Sullinger missing a pair late as well.

Pressed on his woes, Rondo admitted he's at a loss for his poor percentage.

"I don’t have a clue really, still trying to figure it out," he said. "I continue to work on my game and especially get some more free throws up."

Coach Brad Stevens has said that Rondo frequently has returned to the team's practice facility after games to work on free throws in hopes of solving his issues. A team with a thin margin for error, the Celtics absolutely need Rondo to be confident at the stripe to help their chances of pulling out the sort of wins that have evaded them to this point.

A collection of news, notes, and nuggets from Friday's matinee:

• Final 4 company: Stevens isn't the only one in his family who can now claim a Final Four appearance. His cousin, Alex McInturf, is a senior midfielder for the Final Four-bound Williams College women's soccer team. "That’s pretty sweet, isn’t it?" Stevens said. "My first cousin is playing in the women’s soccer Final Four next week with Williams, so I wear my Williams sweatshirt around proudly right now. I got a chance to see her play [earlier] this year over there. We’ll be back here getting ready for games, but we’ll be paying attention to what’s going on in Kansas City next week." Stevens was asked if he'd offer any words of advice based on his experiences. "No, they’ve got a great coach [Michelyne Pinard], a better coach than I am, so she can handle that."

• Always a Butler fan: Chicago fifth-year guard Jimmy Butler finished with 22 points over 40:35 Friday and hit both the tying and go-ahead free throws late in the game. Even before Friday's tilt, Stevens was raving about Butler. "I think if you had All-Star voting right now, he’d certainly get mine. There’s no question about that," Stevens said. "I think the biggest thing is that he’s a guy that’s always been capable of doing a lot of those things, he’s certainly doing it more consistently. Probably the thing that jumps off the page is that he’s doing it when it matters. He’s a go-to guy and they really go to him when things get tight. They go to him when other teams make runs. ... He’s really impressive, and I'm really happy for him. It’s a great story of development." To be fair, with the last name Butler, Stevens' opinion of the player clearly is biased from his past coaching gigs.

• Turkey talk: Stevens invited all of his players to the house for Thanksgiving dinner after the team practiced on Thursday afternoon. Some support staff took the invite, but none of the players accepted. "I guess they were scared of us making the meal," Stevens quipped. "We had a couple staff members over and families. Thanksgiving for us has always been a family holiday, but it's an extended basketball family holiday because I’ve spent very few Thanksgivings at home, most of them have been on the road at these preseason tournaments when I was in college. It’s one of those deals where, we’ve always tried to share it with staff. We had a good practice; it was good to see everybody. Then they went on their own way." Stevens did leave his players with one helping of advice: "Take a walk at night," Stevens said. "Because the last thing we want to do is eat and all sit on the couch the rest of the night and get up for the first time and move today."