For two and a half years on the ATP tennis circuit, the pairing of world number two Andy Murray and super coach Ivan Lendl terrorised the rest of the tour.
From 2011 to 2014, the pair won the US Open, an Olympic gold medal, and of course, broke Britain's duck at Wimbledon, with Murray becoming the first British male to win the title in 77 years.
However, the pair split by mutual consent in 2014, with Lendl keen to focus on other commitments and unable to obligate to the time constraints of full time tennis coaching.
With Lendl went the maturity and consistency he provided Murray with, and over time, the more offensive game style the Czech instilled in him went also.
It is unknown what impact the split had on Murray's mentality or confidence. But either way, he had stopped hitting his second serves with purpose. He stopped taking on short balls and returns. He stopped attacking the net
All these improved facets of his play were key under Lendl's instruction, and were prominent features of Murray's big wins, such as Grand Slam Finals and the Olympic gold medal match.
Whilst he maintained the high level of tennis we are accustomed to from the British number one, the difference came in the big matches. It was in the Grand Slam Finals and semi-finals that Murray had lost his edge.
In particular, his form under Lendl's replacement Amalie Mauresmo was at times criticised, with former British female number one Annabel Croft claiming that she may not be the right coach for Murray.
After the inevitable split with Mauresmo came, along with two more Grand Slam Final losses at the Australian and French Opens, both at the hands of Novak Djokovic, Murray put in another call to Lendl to see if he would be interested in re-joining his team.
After two years working at the United States Tennis Association, Lendl was back for Murray's first match at Queen's Club in 2016, which he won for a record fifth time.
While he did not have to face the prospect of Novak Djokovic at The Championships this year, Murray more than convinced us of two things at Wimbledon this year.
First of all, there was little doubt Murray was deserving of his trophy. The Scot was all over his opponent, first time Grand Slam Finalist Milos Raonic.
Despite a straight sets win, the biggest discrepancy came at the net, with Murray completely dominating Raonic in an area of play he prides himself on.
The figures read the Canadian as having won 46 of his 74 points at the net. Murray on the other hand, lost only 5, winning an astonishing 17/22.
It is this fearless game style that a Lendl coached player is representative of, such as Andy Murray from the years 2011-14. The US Open champion. The Olympic champion. The Wimbledon champion.
What else did he convince us of? That a pairing of Andy Murray and Ivan Lendl – 11 Grand Slam titles between them – is enough to shake off the monopoly Novak Djokovic posses over men's tennis right now.
Murray is back to being a champion, back to where he belongs, and it is Ivan Lendl who is helping take him there.
A man who made his fame almost more for overcoming his own haunting mental demons than the success he enjoyed is now helping another prodigious tennis talent do the very same.
It's great for Andy Murray. It's even better for tennis.