Michael Phelps' medal count hit 21 on Friday as he extends his lead as the most decorated Olympian in Olympic Games history. However, he is still not done! Saturday will see Phelps in Olympic action one final time in the 4x100M Medley Relay, in what will be his final appearance at an Olympic Games ever.

The amazing achievement by Phelps, although not entirely unexpected, has still left fans and analysts alike stunned.

Many felt that Phelps would show his age at these London 2012 Olympics and would perhaps come up short more often than not. Although there have certainly been signs that he is not at his 2008 Beijing peak, he is still the most successful swimmer at the Games once again.

For the 2012 Summer Olympics in London, Phelps originally stated he would never do eight events again, and would instead try new events. However, at the 2012 United States Olympic Trials, the qualifying meet for the 2012 Summer Olympics, Phelps qualified in the same eight events that he swam in Beijing in 2008. He later dropped the 200-meter freestyle from his program, as he stated he wanted to focus on the 4×100-meter freestyle relay.

So can Phelps go one more and achieve an unprecedented 22nd Olympic medal before he retires? Phelps' mother, his ever animated biggest fan Debbie, has reportedly urged her son to keep going onto Rio de Janeiro in 2016, but Phelps has assured that with the 4x100 Meter Medley Relay on Saturday he will be done.

Here is a look at the amazing achievement of Michael Phelps; undoubtedly the greatest swimmer in Olympic history, and some claim the greatest Olympian of all time. Here are how his 21 Olympic medals have been won so far. Perhaps there will be a 22nd to add to that before Saturday is out.

2004 Olympic Games in Athens

Gold      100 m butterfly - 51.25 (OR)

Gold      200 m butterfly - 1:54.04 (OR)

Gold      200 m individual medley               - 1:57.14 (OR)

Gold      400 m individual medley               - 4:08.26 (WR)

Gold      4×200 m freestyle            - 7:07.33 (NR)

Gold      4×100 m medley               - 3:30.68 (WR)

Bronze  200 m freestyle - 1:45.32 (NR)

Bronze  4×100 m freestyle            - 3:14.62

2008 Olympic Games in Beijing

Gold      100 m butterfly - 50.58 (OR)

Gold      200 m butterfly - 1:52.03 (WR)

Gold      200 m freestyle - 1:42.96 (WR)

Gold      200 m individual medley               - 1:54.23 (WR)

Gold      400 m individual medley               - 4:03.84 (WR)

Gold      4×100 m freestyle relay - 3:08.24 (WR)

Gold      4×200 m freestyle relay - 6:58.56 (WR)

Gold      4×100 m medley relay    - 3:29.34 (WR)

2012 Olympic Games in London

Gold      100 m butterfly - 51.21

Gold      200 m individual medley               - 1:54.27

Gold      4×200 m freestyle relay - 6:59.70

Silver     200 m butterfly - 1:53.01

Silver     4×100 m freestyle relay - 3:10.38