The brinkmanship among Chelsea galleries aiming for museum-level cred is ratcheting up another notch this week. Gagosian has announced it will keep its 21st Street branch open on Mondays, showing off its formidable Monet show six days a week — news that David Zwirner is proudly countering with the display of Ed Kienholzs sprawling 1961-62 Roxys installation. A few blocks away, Matthew Marks has lined up an Anne Truitt retrospective, and Fredericks & Freiser is displaying some early cuts from its star painter, John Wesley. Two large, potentially smart group shows and a William Pope.L exhibition round out a week of major openings. And if those events don’t tempt you into the mild pre-summer weather for some art-touring, more than 50 spaces have organized special programs (and extended hours) for New York Gallery Week, which are well worth a peek.

Thursday

John Wesley, “May I Cut In? Important Paintings from the Early 70’s,” at Fredericks & Freiser, 536 West 24th Street, through June 12, opening Thursday, May 6, 10 a.m.–6 p.m.

It takes a singular talent to earn the admiration of both Miuccia Prada and Donald Judd, but such is the accomplishment of John Wesley, whose work has been featured in exhibitions at the designer’s Fondazione Prada and the artist’s Chinati Foundation. The 12 paintings here, some not seen for nearly four decades, show the artist honing his inimitable brand of cartoon portraiture, unfailingly presented against a light-blue background. In one, four tuxedo-clad vampires approach a blond woman who throws her head back in submission, awaiting a bite. Like much of Wesley’s sublime work, it contains a curious admixture of the humorous and the horrible.

Reflection,” at Nathan A. Bernstein & Co. Ltd., 21 East 65th Street, through July 1, opening Thursday, May 5, 6–8 p.m.

“I’ll be your mirror / Reflect who you are,” Velvet Underground chanteuse Nico once sang, adding, “In case you don’t know.” It’s an apt mission statement for contemporary artists, and one that the 15 artists in this show — including Warhol, Lichtenstein, and Benglis — take literally, to varying degrees. It shouldn’t be hard to catch a reflection off James Lee Byars untitled circle of gold paper, nor Rob Wynnes Where Else, poured and mirrored glass that spells its title. However, using Jacob Kassays canvas, painted silver and then burned through electroplating, could present a greater challenge; it's nonetheless a nice representation of reflection gone awry.

Saturday

Twenty Five,” at Luhring Augustine, 531 West 24th Street, through June 19, opening Saturday, May 8, 6–8 p.m.

When the histories of the past 25 years of the art market are written, dealers Lawrence Luhring and Roland Augustine seem likely to earn starring roles, having introduced artists like Rachel Whiteread, Albert Oehlen, and Yasumasa Morimura to U.S. audiences. Celebrating its silver anniversary, their gallery is showing some the seminal works it first displayed, like Janine Antonis 1993 Lick and Lather, self-portraits built with soap and chocolate; a 1992 Martin Kippenberger self-portrait; and Cady Nolands 1989 Crate of Beer. The painter Josh Smith — one of the gallery's rising stars — has designed a book for the occasion, collecting archival invitations and photographs.

Anne Truitt, “Sculpture 1962–2004,” at Matthew Marks Gallery, 522 West 22nd Street, through June 26, opening Saturday, May 8, 6–8 p.m.

Following the Hirshhorn Museums towering Truitt retrospective in 2009 — her first major exhibition in 35 years — Matthew Marks is presenting 16 of her rectangular totems, many from that D.C. show. Painted in a stunning array of colors — from a deep, rich raspberry red to a solemn brown and a bracing yellow, her objects prove the affective power of even the most reduced forms. It took some time — this is her first New York show in nearly 20 years — but Truitt is joining the pantheon of great American artists, boldly.

William Pope.L, “landscape + object + animal,” at Mitchell-Innes & Nash, 534 West 26th Street, through June 19, opening Saturday, May 8, 6–8 p.m.

It’s impossible to dislike an artist whose traveling survey show last decade was winningly titled “The Friendliest Black Art in America.” His second show at MIN includes a video viewed through a chimney, PVC paintings printed with the phrase “NEGRO IDEA,” and a drawing that reads, “YELLOW PEOPLE ARE BORING.” It’s not necessarily market-friendly material, but a curious poeticism — the PVC works are alluring and fragile, the drawings nimbly constructed — prevents it from being simple agitprop. Performances of Pope.L’s Cusp piece will run on Saturdays throughout the exhibition. Expect Obama masks, oversize pajamas, green paint, and mounds of dirt.