Julia Fischer’s 2 back-to-back concerts of solo Bach were to be a highlight of March’s concert calendar here. But “due to family concerns,” Fischer, the German violinist who has wowed University Musical Society audiences on past visits here, canceled the North American tour that was to bring her to Rackham Auditorium next week, March 24 and 25.

The hall won’t be dark those nights, though. The UMS, in its usual resourceful fashion, has replaced Fischer with 2 artists Ann Arbor should hear but hasn’t yet: the cellist Pieter Wispelwey on Wednesday, March 24 and the violinist Jennifer Koh on Thursday, March 25. Both appear unaccompanied, and both play concerts that, in the spirit of Fischer’s planned recitals, take the music of Bach as a central focus.

For his program, Wispelwey, 48, a Dutch-born cellist (and the 1st cellist to win the Nettherlands Music Prize), has chosen to pair 2 of Bach’s cello suites with 2 20th century suites for solo cello by Britten.

Listen to Pieter Wispelwey "Bach: Suite no.1 in G dur BWV 1007: Menuet 1 & 2"

The program is perfect for a player who is equally at home on period and modern cellos and whose repertoire ranges from Baroque to contemporary It will be an evening to compare and contrast: the Bach 1st suite in G Major and the Britten Suite No. 1 constitute the 1st half of the bill; post-intermission, it’s the Bach 2nd suite in d minor and the 3rd and last of Britten’s suites.

Thursday evening, March 25, Koh, a 30-something winner of the International Tchaikovsky Competition in Moscow, the Concert Artists Guild Competition and the Avery Fisher Career Grant, takes up her violin for some of the same repertoire Fischer was to play: the 2nd and 3rd of Bach’s partitas for unaccompanied violin.

Listen to Jennifer Koh "Bach: Partita No. 2 in D minor for Solo Violon, BMV 1004 - Allemanda"

But, like Wispelwey, she expands her focus to include music of our time. Included on her program are the Ysaÿe 2nd sonata for unaccompanied violin (“Obsession”); Saariaho’s “Nocturne, in memory of Witold Lutoslawski;” Carter’s “Fantasy: Remembering Roger;” and Salonen’s “Lachen verlernt” (with film projection by Tal Rosner).

Wispelwey and Koh have something more in common than programs of Bach and beyond: both have reputations as mesmerizing recitalists. Ann Arbor could be in for 2 nights of powerful music making.

UMS has mailed a letter to all ticket holders for the Fischer concerts concerning the cancellation; their tickets are valid for these concerts should they wish to use them. Contact UMS for details or to purchase tickets for Wispelwey or Koh: 734-764-2538 (Michigan League Ticket Office) and online at the UMS web site. Tickets are $20-$42.

Susan Isaacs Nisbett is a free-lance writer who covers classical music and dance for AnnArbor.com.