In 1932—by then holder of the British Empire record for the mile—Lovelock competed in the 1932 Summer Olympics in Los Angeles, and placed 7th in the final of the 1500 metres event.
The following year, he set a world record of 4:07.6 in the mile when running at Princeton against its emerging champion Bill Bonthron. Later, in September, he represented New Zealand in the first World Student Games where he renewed his rivalry with the 1500m champion from Los Angeles in 1932, Luigi Beccali. Beccali edged Lovelock in the final and equalled the world record for the event. In 1934 Lovelock won the gold medal in the mile at the British Empire Games. He also lost some races, and believed that he could only make one supreme effort in a season.
The highlight of Lovelock’s career came in 1936, when he won the gold medal in the 1500 m at the Berlin Olympics, setting a world record in the final (3:47.8). Lovelock had plotted ever since his defeat at Los Angeles and developed a revolutionary tactic. The race is regarded as one of the finest 1500 m Olympic finals and included one of the finest fields assembled. The final was a culmination of the first great era of mile running from 1932–36 in which the world records for the 1500m and mile were broken several times.
Apart from Lovelock and the American mile world record holder Glenn Cunningham who broke Lovelock’s record a year later in 1934, also at Princeton, Bonthron, the 1932 Olympic Games 1500m champion at Los Angeles, Luigi Beccali and the emerging English champion Sydney Wooderson raced in Berlin. Bonthron, who held the world 1500m record, failed to make the US team, while Wooderson was found to have a fracture in his ankle and missed the final. The silver medalist in Los Angeles, John ‘Jerry’ Cornes also raced in Berlin along with the Swedish champion Erik Ny and the outstanding Canadian athlete Phil Edwards and another American Gene Venzke, who had been regarded as the favourite for the 1932 title until injury denied him a place in the US team.
In the final, Lovelock beat Glenn Cunningham, who came in second, by making the unprecedented break from 300 m out. Lovelock had been regarded as a sprinter in the home straight but cleverly disguised his plan and caught his opponents napping with a brilliantly-timed move. Cunningham, who also broke the world record in the race, was considered by many to be the greatest American miler of all time. Beccali was third.
Lovelock, who was the captain of the New Zealand Olympic team, raced once more for the British Commonwealth after Berlin and his last race was back at Princeton en route to a Government-sponsored trip to New Zealand where he was beaten by another of the Olympic finalists Archie San Romani. Lovelock maintained his interest in athletics until at least the outbreak of the Second World War as a newspaper contributor.