As I'am thinking, Federer was a true opponent at Roland Garros and had always chances against Younger Nadal, more than Thiem who if often designed as the Prince of Clay, and against Older Nadal.
What was for your the Federer's best chance against Nadal at Roland Garros
Let's try to analyze the matches
2005 :
It was the first FO of Nadal and Federer was the undisputed number 1 at this time. There was no mental advantage from Nadal against Federer either no aura of invincibility. Federer was leading 3-2 40-15 (again a 40-15...) in the fourth set then his forehand betrayed him. Lost 4 games in a row
Nadal was still a pure retriever then. He was faster than ever but his backhand and serve were weak and Federer 2005 forehand was very flat and brutal . Federer was maybe too confident at the time and maybe underestimated Nadal a lot (with his Miami come-back). I think he should have prepared better.
2006 :
Federer was at his absolute peak this year. He gave Nadal hard and tight matches in Monte-Carlo and espiecially Rome. He never played so well on clay.
Federer took the first set 6-1 against Nadal with commanding play. He was leading 40-0 at 0-1 and then Nadal broke him by good play and then Federer lost the plot . Had 4 BP for a 3-1 lead in the third set. Didn't take his opportunities (at 30-40, Federer missed a forehand finish after having dominated the rally, the others were very good saved by Nadal). Lost the fourth in a tie-break.
For me, it was the best chance of Federer this year , as Nadal hasn't became the monster he will be. I'am still convinced that the infamous 2 MP missed by Federer at Rome changed the rivalry and sealed the aura of invincibility of Nadal on clay. If Federer, I'am sure that Federer would have won the 2006 FO Final.
2007 :
Federer has beaten Nadal at the Hambourg Final, even bageled him. You could think that Federer was getting closer to beating Nadal.
Story of the final : the terrible Federer's break point conversion during the match :
1/17 (5,8%)
1) 0/10 for the first set (7 for a 4-2 lead, 3 for level the match at 4-4). Nadal was 2/2 on BP
2) 2 BP to take the second set 6-3 and serve in first in the third set
3) 1 BP for a 2-0 lead in the fourth set
( Gold Medal : the AO 4R 2019 with 0/12 (0%) against Tsitsipas)
( Silver Medal : the Wimbledon 2008 F with 1/13 (7,69%) against Nadal)
( Bronze Medal : the USO 2015 Final with 4/23 (17,3%) against Djokovic)
With more temerity, he should have won the first set.
In terms of quality, it was his best match. Federer played two excellent first sets, even making great winners with his backhand and then couldn't keep his level for the rest of the match.
2011 :
Federer had stopped the invincible winning streak of Djokovic and was playing his best FO ever. Nadal was shaky during this FO (pushed to the brink by Isner, laborious against Andujar) . The balls were lighter this year and Federer offense was more rewarded . It was almost Hardcourt tennis on clay.
Federer quickly stormed Nadal in the first. Had a set point at 5-2, barely missed with a drop-shot. Then Federer dropped his level and Nadal raised his. Federer lost 7 games in a row.
Federer saved 1 (or 2 ?) SP at 5-4 on the Nadal serve. But played an putrid tie-break (TWO second serve missed returns, a forehand into the net, complacent smash)
Federer has 3 BP for a 1-0 lead in the fourth set. Well saved by Nadal. Then Federer completely collapsed and lost the set 6-1
2019 :
Rejunevated Federer has turned the tables of the rivalry. He has won the four last matched against Nadal (with the most important one : the AO 2017 Final) and maybe Federer was in Nadal's head. People were wondering if Federer could apply his new succesfull playing pattern against Nadal on clay (the Néo-Backhand for exemple). The answer was : No.
Federer was leading 2-0 40-30 on the second set. He was 40-15 (again !) at 4-4 on his serve. Lost it and the set. Tamely lost the third set 6-2
The windy conditions have sabotaged Federer.
No need to put the 2008 beatdown in the chances list.
What was for your the Federer's best chance against Nadal at Roland Garros
Let's try to analyze the matches
2005 :
It was the first FO of Nadal and Federer was the undisputed number 1 at this time. There was no mental advantage from Nadal against Federer either no aura of invincibility. Federer was leading 3-2 40-15 (again a 40-15...) in the fourth set then his forehand betrayed him. Lost 4 games in a row
Nadal was still a pure retriever then. He was faster than ever but his backhand and serve were weak and Federer 2005 forehand was very flat and brutal . Federer was maybe too confident at the time and maybe underestimated Nadal a lot (with his Miami come-back). I think he should have prepared better.
2006 :
Federer was at his absolute peak this year. He gave Nadal hard and tight matches in Monte-Carlo and espiecially Rome. He never played so well on clay.
Federer took the first set 6-1 against Nadal with commanding play. He was leading 40-0 at 0-1 and then Nadal broke him by good play and then Federer lost the plot . Had 4 BP for a 3-1 lead in the third set. Didn't take his opportunities (at 30-40, Federer missed a forehand finish after having dominated the rally, the others were very good saved by Nadal). Lost the fourth in a tie-break.
For me, it was the best chance of Federer this year , as Nadal hasn't became the monster he will be. I'am still convinced that the infamous 2 MP missed by Federer at Rome changed the rivalry and sealed the aura of invincibility of Nadal on clay. If Federer, I'am sure that Federer would have won the 2006 FO Final.
2007 :
Federer has beaten Nadal at the Hambourg Final, even bageled him. You could think that Federer was getting closer to beating Nadal.
Story of the final : the terrible Federer's break point conversion during the match :
1/17 (5,8%)
1) 0/10 for the first set (7 for a 4-2 lead, 3 for level the match at 4-4). Nadal was 2/2 on BP
2) 2 BP to take the second set 6-3 and serve in first in the third set
3) 1 BP for a 2-0 lead in the fourth set
( Gold Medal : the AO 4R 2019 with 0/12 (0%) against Tsitsipas)
( Silver Medal : the Wimbledon 2008 F with 1/13 (7,69%) against Nadal)
( Bronze Medal : the USO 2015 Final with 4/23 (17,3%) against Djokovic)
With more temerity, he should have won the first set.
In terms of quality, it was his best match. Federer played two excellent first sets, even making great winners with his backhand and then couldn't keep his level for the rest of the match.
2011 :
Federer had stopped the invincible winning streak of Djokovic and was playing his best FO ever. Nadal was shaky during this FO (pushed to the brink by Isner, laborious against Andujar) . The balls were lighter this year and Federer offense was more rewarded . It was almost Hardcourt tennis on clay.
Federer quickly stormed Nadal in the first. Had a set point at 5-2, barely missed with a drop-shot. Then Federer dropped his level and Nadal raised his. Federer lost 7 games in a row.
Federer saved 1 (or 2 ?) SP at 5-4 on the Nadal serve. But played an putrid tie-break (TWO second serve missed returns, a forehand into the net, complacent smash)
Federer has 3 BP for a 1-0 lead in the fourth set. Well saved by Nadal. Then Federer completely collapsed and lost the set 6-1
2019 :
Rejunevated Federer has turned the tables of the rivalry. He has won the four last matched against Nadal (with the most important one : the AO 2017 Final) and maybe Federer was in Nadal's head. People were wondering if Federer could apply his new succesfull playing pattern against Nadal on clay (the Néo-Backhand for exemple). The answer was : No.
Federer was leading 2-0 40-30 on the second set. He was 40-15 (again !) at 4-4 on his serve. Lost it and the set. Tamely lost the third set 6-2
The windy conditions have sabotaged Federer.
No need to put the 2008 beatdown in the chances list.