Edouard Louis Joseph, baron Merckx (Dutch pronunciation: ['merks]; born 17 June 1945), better known as Eddy Merckx, is a Belgian former professional road and track bicycle racer who is widely seen as the most successful rider in the history of competitive cycling. His victories include an unequalled eleven Grand Tours (five Tours of France, five Tours of Italy, and a Tour of Spain), all of the five Monuments, three World Championships, the hour record, every major one-day race other than Paris-Tours, and extensive victories on the track. Born in Meensel-Kiezegem, Brabant, Belgium, he grew up in Woluwe-Saint-Pierre where his parents ran a grocery store. He played several sports, but found his true passion in cycling.

Edouard Louis Joseph Merckx was born in Meensel-Kiezegem, Brabant, Belgium on 17 June 1945 to Jules Merckx and Jenny Pittomvils. Merckx was the first-born of the family. In September 1946, the family moved to Woluwe-Saint-Pierre, in Brussels, Belgium in order to take over a grocery store that had been up for lease. In May 1948, Jenny gave birth to twins: a boy, Michel, and a girl, Micheline. As a child Eddy was hyperactive and was always playing outside.  Eddy was a competitive child and played several sports, including basketball, boxing, football, and table tennis. He even played lawn tennis for the local junior team. However, Merckx claimed he knew he wanted to be a cyclist at the age of four and that his first memory was a crash on his bike when he was the same age. Merckx began riding a bike at the age of three or four and would ride to school every day, beginning at age eight. Merckx would imitate his cycling idol Stan Ockers with his friends when they rode bikes together.  In summer 1961, Merckx bought his first racing license and competed in his first official race a month after he turned sixteen, coming in sixth place. He rode in twelve more races before winning his first, at Petit-Enghien, on 1 October 1961. In the winter following his first victory, he trained with former racer Felicien Vervaecke at the local velodrome. Merckx won his second victory on 11 March 1962 in a kermis race. Merckx competed in 55 races during the 1962 calendar year; as he devoted more time to cycling, his grades at school began to decline. After winning the Belgian amateur road race title, Merckx declined an offer from his school's headmaster to have his exams postponed, and dropped out of school. He finished the season with 23 victories to his name.  Merckx was selected for the men's road race at the 1964 Summer Olympics, where he finished in twelfth position. Later in the season, he won the amateur road race at the UCI Road World Championships in Sallanches, France. Merckx remained an amateur until April 1965, and finished his amateur career with eighty wins to his credit.

Answer the following question by taking a quote from the article: When did he start competing professionally?
Merckx was selected for the men's road race at the 1964 Summer Olympics, where he finished in twelfth position.