His career stalled from 2009 to 2019, however, by a combination of his belated release from the Chinese boxing authorities to turn professional, the managerial and legal fiasco of two successive fringe promotional companies, and his visa problems.

[16] At the 2005 World Amateur Boxing Championships in China, he beat Vugar Alekperov 20:11 before losing to eventual champion Odlanier Solis (17:7).

Zhang was highly regarded by American promoters by 2009[4][25] but his career stalled between 2009 and 2019 owing to a combination of his duties to Chinese national boxing obligations, mismanagement and accompanying legal issues, and his visa problems.

[30][31][32] The highlight of that training were 11 bouts between the Chinese and American national boxing teams in Manhattan promoted as "Empires Collide", which Zhang defeated Danny Kelly Jr 16:8 in the main fight.

[36] He was finally released by the Henan Provincial Combat and Weightlifting Center after he competed in the 2012 Olympics and won the gold medal for 2013 National Games of China.

[28] Before 2014, Zhang was a typical product of the Chinese state-centric sports development policy known as juguo tizhi (举国体制), with all his training schedule, coaching, insurance, housing, and meals arranged and paid for by the Henan Provincial Combat and Weightlifting Center.

[27] The Henan Provincial Department of Sports secured public institution positions for athletes like Zhang should they retire in China.

[26][18][2] When he moved to the United States on March 8, 2014, he had to manage and self-finance aspects of his life which had previously been handled by the Henan Provincial Combat and Weightlifting Center.

[2] Zhang's slow rise to prominence was also contributed to the debacle that saw his first and second promotional companies go out of business in 2014 and 2020 respectively and the legal chaos that followed.

After the 2008 Olympics, Dino Duva built relationships with the National Boxing and Taekwondo Center of the Department of Sports of China and obtained exclusive rights to market all Chinese boxers.

[27][41] David Itskowitch, Roc Nation's founding chief operating officer of boxing, abruptly resigned in July 2016 and Duva's influence grew after.

[27] In 2024, Zhang's co-manager recalled his promoter tried to stop him leaving by intimidation, dragging him into legal battles and refusing to line him up in fights.

After moving to the United States in 2014, Zhang rarely visited China to see his parents, wife and son (born 2010[27]) because he had to reapply for single-entry working visa every time.

[50] Zhang's majority draw with journeyman Jerry Forrest on February 27, 2021, was a landmark moment in his career not because it was the first fight he did not win (22–0–1), but because it finally highlighted how poor his nutrition was.

[51] He was diagnosed with iron-deficiency anemia, high enzyme levels, low-level renal failure, electrolyte disorder, liver dysfunction and severe dehydration.

[18] Unfamiliar with Miami's high humidity, Zhang's water intake during his stay at hotel was insufficient and he suffered from severe dehydration.

[2] When Zhang was discharged from hospital, his first words to his managers were the Chinese idiom, fang hu gui shan, lit.

[59] His fight against Hrgović was rescheduled for 20 August 2022, in Jeddah, Saudi Arabia, on the undercard of Oleksandr Usyk vs Anthony Joshua II.

[61][62] It was reported on 20 January 2023, 39 year old Chinese contender Zhang was to challenge Joe Joyce (15-0, 14 KOs) for the interim WBO heavyweight title at on 15 April in London.

[63] On 2 February, Queensberry Promotions announced Joyce would defend his WBO Interim heavyweight title at the Copper Box Arena in London against Zhang on 15 April.

Frank Warren explained, whilst they wanted to keep Joyce busy before an inevitable world title fight, he would still take on tough challenges.

The rematch was scheduled to take place at the OVO Arena Wembley in London on 2 September on BT Sport in the UK and ESPN+ in the United States.

On 29 June, a press release confirmed all the details of the fight, with the card taking place on the newly rebranded TNT Sport, following the joint venture between BT Group and Warner Bros.

[90][91][92][93] After the fight, Warren said Joyce would need to consider retirement following back-to-back defeats as it would be a hard journey back to mandatory status.

Joyce stated he was open to a possible rematch with Daniel Dubois, who in August, was stopped in his attempt to capture the world titles from Usyk.

[96] On 15 January 2024, only weeks after defeating Deontay Wilder, it was announced that Joseph Parker (34-3, 23 KOs) would challenge Zhang for the WBO interim title, with the fight scheduled to occur on 8 March, as the co-main event of the Knockout Chaos event headlined by Anthony Joshua vs. Francis Ngannou, at Riyadh's Kingdom Arena.

Parker won majority of the second half by being a bit busier than Zhang, who was being patient, but looked like he wanted to land the knockout blow.

[112] Zhang faced German heavyweight contender Agit Kabayel on February 22nd, 2025 on the undercard of Beterbiev-Bivol 2 from Riyadh, Saudia Arabia.

This came to public awareness on February 27, 2021, after the fight with Jerry Forrest, when he was hospitalized and diagnozed with iron-deficiency anemia, high enzyme levels, low-level renal failure, electrolyte disorder, liver dysfunction and severe dehydration,[2][52] with his heavy intake of tea being attributed as one of the factors,[2] along with his poor management of nutrition and fitness at hotel during COVID-19 quarantine in Miami.

[18] To distract himself from Chinese tea culture, he developed other hobbies, such as constructing cameras, barbecue grills and car washing equipment.