There was a change of plans on Tuesday for lightweight world titleholder Raymundo Beltran's first defense. He will face Jose Pedraza instead of Roman Andreev.

Last week, Top Rank was the only bidder with an offer of $252,000 to win the purse bid for Beltran's mandatory defense against Russian contender Andreev. The fight was scheduled to headline a Top Rank Boxing on ESPN card on Aug. 25 at the Gila River Arena in Glendale, Arizona, not far from Beltran's home base in Phoenix.

However, Andreev's team informed Top Rank on Monday that Andreev had an appendicitis attack and underwent surgery, leaving him unable to train for the fight. So he has withdrawn, paving the way for Pedraza to move into his spot.

"Andreev's manager sent us a note telling us that Andreev had the operation to remove his appendix and that he was pulling out of the fight," Top Rank chairman Bob Arum told ESPN.

Next in line in the WBO's lighweight rankings is Pedraza, the Top Rank-promoted fighter the company hoped to match Beltran with in the first place -- once the proposed unification fight with Vasiliy Lomachenko had to be put on hold due to Lomachenko's shoulder injury and subsequent surgery.

However, when Top Rank tried to get approval for the Beltran-Pedraza bout it was told Beltran had to first make the mandatory defense against the 32-year-old Andreev (21-0, 15 KOs).

"Full speed ahead with Pedraza now with no impediments," Top Rank vice president Carl Moretti said Tuesday. "Stylistically, I think it's a sensational matchup because usually when Ray Beltran fights he's never in a boring fight. And Pedraza is extremely confident and we believe that he is a much better fight at 135 pounds than at 130."

Beltran (35-7-1, 21 KOs), 36, a Mexico native, won a vacant 135-pound world title in his fourth chance on Feb. 16 when he outpointed Paulus Moses during a bruising battle in Reno, Nevada.

Pedraza (24-1, 12 KOs), 29, of Puerto Rico, is a former junior lightweight world titleholder who lost his belt by seventh-round knockout to Gervonta Davis in January 2017. He eventually signed with Top Rank and returned to the ring as a lightweight in March after a 14-month layoff.

He has won two fights in a row, including a unanimous 10-round decision in an all-action fight against Antonio Moran on June 9 in Las Vegas on the Terence Crawford-Jeff Horn undercard.

The Beltran-Pedraza winner is the likely opponent to face Lomachenko (11-1, 9 KOs) in a unification fight in December, when Lomachenko is expected to return following surgery to repair the torn labrum he suffered in his right shoulder during the second round of his 10th-round knockout of Jorge Linares to win a lightweight world title on May 12.

Moretti also told ESPN that newly crowned junior featherweight world titleholder Isaac Dogboe will make his first defense in the co-feature against Hidenori Otake.

Dogboe (19-0, 13 KOs), 23, of Ghana, won a 122-pound world title on April 28 in Philadelphia when he knocked out Jessie Magdaleno in an enthralling fight of the year candidate. Dogboe survived a first-round knockdown and stormed back to drop Magdaleno in the fifth round and twice more in the 11th round for the victory.

Otake (31-2-3, 14 KOs), 37, of Japan, has won nine fights in a row since losing the only time he has fought outside of his home country -- a unanimous decision when he challenged then-junior featherweight titleholder Scott Quigg in 2014 in Liverpool, England.

"Otake is a very solid fighter from all indications," Moretti said. "Dogboe is coming off the sensational win over Magdaleno. He's now a must-see fighter."