The 21-year-old claimed a unanimous judges' decision win over Crews in a four-round super middleweight fight after enjoying the most successful amateur career for an American woman.

Shields earned a total score of 40-36 on all three of the judges’ scorecards in an entertaining fight on the undercard of the Sergey Kovalev Andre Ward light heavyweight title fight at the T-Mobile Arena in Las Vegas.

Shields became the first American woman to win a boxing gold medal when she won the middleweight title as the sport made its debut at London 2012

She retained her title at Rio 2016. 

The action-packed affair had the fighters trading hard blows against the ropes just seconds after the opening bell.

But it was Shields who was able to land the first accurate attack on her opponent.

Crews responded nearly blow-for-blow but a strong left hook to the face from Shields gave her the upper-hand in round one.

In the second, Crews attempted to match Shields’ aggression but was ineffective in launching a prolonged attack as her frustration began to show when she shoved Shields down to the canvas and received a stern warning from the official as a result.

Keen to continue her dominant style, Shields replied with a number of body shots that began to inflict damage on her opponent.

Crews found some success with well-timed counters in the second half of the fight and landed her best punch of the night halfway through the third.

The right-hand counter landed perfectly on Shields but the blow seemed to have little to no effect on her opponent as Shields refused to retreat.

In the fourth and final round, Crews received another warning for pushing Shields, an assault that angered the gold medallist.

Visibly upset and with her first professional win secure, Shields went on the offensive landing a thumping right hook on Crews.

It failed to have the desired knockout effect but, with seconds left, it did not matter as Shields had already done enough to secure the win.