Backstage at the Riviera Hotel in Las Vegas with Engelbert Humperdink on May 25, 1972

From Elvis Day By - "Elvis flies to Las Vegas May 24th and on Sunday night attends Glen Campbell's show at the Hilton and on May 30th Elvis returns to LA before flying home to Memphis the following night." Engelbert Humperdinck performed at the Riviera from May 24th to June 25th