Fan vote: Zinedine Zidane's Real Madrid in UCL or Michael Phelps at Olympics?

Welcome to ESPN's fan vote, where you, the reader and sports fan, will decide which individual or team has been the most dominant in the 21st century.

For our second match-up, we have Zinedine Zidane's UCL-conquering Real Madrid up against a modern legend in Michael Phelps. One team reigned supreme over Europe for three years, while the other ruled the swimming pool, but who dominated the field like no other?

(Please vote in the poll at the bottom of this page to decide the winner.)

Zidane, Ronaldo, and Real Madrid's UCL three-peat (2016-2018)

Luck and form often play a bigger part in knockout competitions than consistency, but three straight Champions League titles do not happen by accident.

Real Madrid were far from perfect, and came close to exiting on multiple occasions during their three title-winning campaigns. Yet, somehow, Zinedine Zidane's men made clutch a habit, breaking hearts (and arms) along the way and producing some of the most spectacular moments of the UCL in this century.

Even as they stumbled domestically, they turned up with renewed vigour at the European knockout stages time and again, with Cristiano Ronaldo breaking new records, Sergio Ramos defying all critics and even unsettled players like Gareth Bale producing moments of magic.

Michael Phelps at the Olympics (2004-2016)

For 12 years, Michael Phelps dominated the swimming pool. He was probably, in that time, the most dominant individual athlete across sport. Sure, he lost races; he famously lost his last individual Olympic race to Singapore's Joseph Schooling, who looked up to Phelps and had a photo taken with the American when he was 13. But from 2004-16, every time he entered the pool, he was the swimmer to beat. And in a sport with a relatively short shelf life, that's a long time to be so dominant.

No wonder when he retired, after the Rio Olympics, he had these all-time records to his name: Most Olympic medals; most Olympic gold medals; most gold medals at a single Games; most swimming world records. The list goes on. His standout year was 2008, when he won every event, individual or team, he competed in at the Beijing Olympics; and his standout event was the 200m individual medley, which he won in four consecutive Olympics.

(If the poll doesn't load, click here to try again. The poll will close at 5PM IST on Wednesday, June 24)