"Signed, sealed, and delivered: Proud to officially announce that WBA welterweight world champion @MatthysseLucas will put his title on the line against @mannypacquiao in Kuala Lumpur, Malaysia on Saturday night July 14 (U.S. time)," De la Hoya said on Twitter.
Matthysse beat Thailand's Tewa Kiram to win the vacant WBA welterweight belt in January and take his record to 38-4-0.
Filipino Pacquiao, 39, last fought in a unanimous points loss to Australian Jeff Horn in July last year. He is ranked second in the division and has an overall record of 57-6-2.
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(Reporting by Ramiro Scandalo, writing by Andrew Downie, editing by Ed Osmond)
