Tenor Mario Frangoulis will end a series of summer shows performed both locally and abroad, with a performance at the Herod Atticus Theater tomorrow night, joined by a cast of international guests including the celebrity opera duo Opera Babes, acclaimed Spanish pianist Edelmiro Arnaltes and soprano Inva Mula, who has landed leading roles at major opera houses in recent years. The Opera Babes, one of the opera genre’s latest transmitters of the elitist artistic form to the masses, were discovered busking at London’s Covent Garden but have since enjoyed far wider exposure that has included performances at major sporting events. Engagements for the singing pair, Rebecca Knight, a soprano, and Karen England, a mezzo-soprano, both 34, have included opening-ceremony performances for the English FA Cup final and the Champions League Final in Milan, two years ago. The pair, who met on an American tour with the London City Opera singing Mozart’s «Magic Flute,» were trained as serious opera singers. Despite their celebrity sport-gets-couth outings, the Opera Babes would rather not detach themselves too much from «real» opera, they have often emphasized. Also performing tomorrow, Mula, an Albanian soprano, has starred in major productions at lush venues, including «Rigoletto» and «La Traviata» at the Arena di Verona, «La Boheme» at the Metropolitan Opera, and again «La Traviata» at the La Scala di Milano. She also contributed vocals to the soundtrack of «The Fifth Element,» which starred Bruce Willis. Born and raised in Tirana, Mula’s career began budding internationally a little over a decade ago following her first prize at the George Ionescu Competition in Bucharest. Arnaltes, the evening’s other visiting performer, established himself as the accompanying pianist for the late Spanish tenor Alfredo Kraus, widely acclaimed as his generation’s finest Spanish tenor. Part of tomorrow’s repertoire will be dedicated to Kraus, who passed away four years ago at the age of 71. Arnaltes will be joined by a second pianist tomorrow, Thodoris Economou, one of Frangoulis’s regular collaborators in recent years, who has also composed the Greek tenor’s most recent work. Frangoulis launched his series of summer performances in Sweden at the Stockholm Festival, where he took part in a two-part concert that featured Julian Lloyd Webber, one of the world’s leading cellists, for the program’s first half and Frangoulis for the second. Both artists were backed by the Swedish Symphonic Orchestra. The Greek tenor’s summer commitments abroad then took Frangoulis to Russia for five sold-out Maria Callas tribute performances at Moscow’s Novaya Opera. These shows, which included excerpts of operas by Verdi and Puccini that marked the late Greek soprano’s extraordinary career were also taken to Cyprus. Frangoulis ended his summer commitments abroad in Helsinki at the city’s 17-day annual festival for a performance with Finnish composer Atso Almila’s 19-member ensemble, Lohja City Orchestra. Tickets for tomorrow’s performance, priced between 30 and 90 euros, are on sale at: the Athens Festival Box Office, 39 Panepistimiou, tel 210.331.8891; Ticket Hellas, tel 210.618.9300; all Metropolis music stores; and Half Note Productions, 3 Terzopoulou, Aghia Paraskevi, tel 210.600.3693.