London (CNN) -- By his own incredibly high standards, 2010 was not a vintage year for 16-time grand slam champion Roger Federer.
The form that Federer showed in trouncing Andy Murray to win the Australian Open in January was soon to desert him. Hampered by a lung infection, he was forced to watch as arch-rival Rafael Nadal reacquainted himself with grand slam glory at both Roland Garros and Wimbledon.
Quarterfinal defeats to Robin Soderling and Tomas Berdych, opponents that an on-fire Federer would normally expect to overcome, not only meant the Swiss maestro relinquished two major titles and the world number one ranking, it also forced him to take stock of his game.
Federer felt he needed an experienced coach on board, somebody who could augment his established support team. "I wanted to get a person in with an outside perspective," Federer told CNN's Open Court program.
The man he chose was Paul Annacone, best-known for guiding another tennis legend, Pete Sampras, to nine grand slam triumphs.
And the partnership has proved to be an unqualified success, with the 29-year-old winning three of his last four tournaments in 2010 including a satisfying victory over Nadal in the final of the season-ending championship in London.
Annacone picks up the story. "Well, first and foremost, Roger is a great player," the 47-year-old American told CNN.
"He has had an incredible career, and the most impressive thing is that he still wants to work hard, get better and generally keep moving in a forward direction.
"It is easy for great athletes to get complacent. Roger couldn't be farther from that. I think it is driven by his love for the game."
Annacone, who worked for the U.S. and British tennis associations after finally splitting with Sampras in 2002, said he has made no major changes to Federer's set-up.
"There have been no magic pills or shortcuts. Just a different voice, with a new perspective and perhaps some different themes to discuss then work on," he revealed.
"With someone as talented and accomplished as Roger, much of my role is about understanding his incredible array of skills and how best to use them to achieve the end result he wants.
"It really has been a great few months and I have enjoyed it immensely."
Federer's renewed drive and determination was there for all to see at the U.S. Open in September, the first big tournament where Annacone's influence was put to the test.
Federer reached the semifinals at Flushing Meadows and had two match-points before losing to Novak Djokovic in the best match of the tournament -- and the Swiss could feel the benefits of another pair of eyes and a change of tactics.
"Paul told me to play more aggressively. I had a tendency to start rallies with a chipped return, but it was a bit predictable for opponents so I worked on a few key areas that we identified," Federer said.
And using his display in New York as a springboard, Federer's form and confidence just got better and better.
In his last eight tournaments of 2010, Federer won four, lost in the final twice and reached the semifinals, including Flushing Meadows, twice.
But the most telling victory came at the ATP World Tour Finals in London, where Federer won the most prestigious title outside the four grand slams for the fifth time, equaling the record held by Sampras and Ivan Lendl.
"It's working really well. Paul's a very likable guy, very simple, very straightforward and we will continue in 2011," Federer said.
Annacone believes that the partnership will continue to bear fruit next year.
"I am confident that the results will take care of themselves if we continue to stay focused on the task at hand," he said.
"I am a big believer in having a good 'big picture' mentality and the ability to focus and sustain focus in the midst of some adversity. I'm really excited about 2011 and seeing what unfolds."