This was posted at a paid forum I'm a member of and I think it's a great analysis of this match so thought I'd share for those debating what to play/prop bets. (Sorry it's so long - well worth it though in my opinion.) 
Nadal takes an imposing 9-0 h2h lead over Mathieu into this game, but the Frenchman has taken the first set on three occasions before falling away and the pair have never met on grass where it appears evident that the Spaniard is struggling most just at the present time.
Rafa has now been pushed to five sets by both Haase and Petzschner in consecutive matches, both delivering a barrage of huge serves and flat, attacking groundstrokes and often hitting through the second seed's unsually shaky defenses.
It took Raf almost four hours in his last match and he looked strangely inconsistent off the ground, his knee appeared to flare up again along with problems with his groin and even the left arm; he lacked momentum and poise especially on the break points and the big men look like being able to earn a lot of cheap points against the Rafa return on the lower-bouncing grass.
He faced persistent questions about being accused of coaching and also taking a medical timeout to stunt his opponent's rhythm, but the most interesting was this; "I never call the physio when I don't have anything (wrong with me), it was because the knee was bothering me a lot... I am a little bit scared about the knee...I had treatment after Monte Carlo and I had the problem against Roddick in the semi-finals of Miami. I am not thinking about retiring or anything like this, that's not going to happen. I have one day and a half to get recovered".
Mathieu looks like he has really benefited from the match fitness he got at the exhibition event in Liverpool, after a convincing win over Gicquel and a hard-fought comeback against a disappointing and choke-filled Youzhny he battled past Thiemo de Bakker in a 4-setter that featured three breakers and some less-than-impressive thought processes and returning from the Dutchman.
The serve-dominated match featured just the single break of serve late in the fourth set the way of Paul-Henri, he seemed the more focused of the two and the one prepared to wait for his chances during the rally. de Bakker often erred with shot selection, misfired his execution and looked extremely sluggish with his footwork, movement and mental strength throughout the match.
After the match, the Frenchman explained; "I am playing well, everything is going right especially my serve and I feel good. It's easier to play when you are confident...I wanted to stay in my chair at the end of the match a little longer than usual. I haven't had many good wins this year. Touch wood this is the end of the barren spell"
Mathieu could definitely be the beneficiary of any Nadal physical issue, and it was clear enough in his last match to suggest that taking him at these short prices under his current circumstances is not worth the risk even if you can feel confident that he will never pull the pin unless he breaks a leg on the court (touch wood, of course).
Mathieu is 1-7 as a 7+ underdog beating Roddick in Montreal back in 2005, but has lost all five 4th round matches at Grand Slam level, has lost 21 of his last 23 against top 10 ranked guys and is just 4 wins from 11 matches against left-handers at all levels since 2009.
Nadal rarely loses these sort of matches and is a rock-solid sub 1.20 prospect especially at the majors, but caution must be treated with the state of his knees (and confidence/momentum/form). Mathieu is confident, in form and is a very good chance at the line and for the over games, providing he backs up physically which was a question mark from his last match.

Nadal takes an imposing 9-0 h2h lead over Mathieu into this game, but the Frenchman has taken the first set on three occasions before falling away and the pair have never met on grass where it appears evident that the Spaniard is struggling most just at the present time.
Rafa has now been pushed to five sets by both Haase and Petzschner in consecutive matches, both delivering a barrage of huge serves and flat, attacking groundstrokes and often hitting through the second seed's unsually shaky defenses.
It took Raf almost four hours in his last match and he looked strangely inconsistent off the ground, his knee appeared to flare up again along with problems with his groin and even the left arm; he lacked momentum and poise especially on the break points and the big men look like being able to earn a lot of cheap points against the Rafa return on the lower-bouncing grass.
He faced persistent questions about being accused of coaching and also taking a medical timeout to stunt his opponent's rhythm, but the most interesting was this; "I never call the physio when I don't have anything (wrong with me), it was because the knee was bothering me a lot... I am a little bit scared about the knee...I had treatment after Monte Carlo and I had the problem against Roddick in the semi-finals of Miami. I am not thinking about retiring or anything like this, that's not going to happen. I have one day and a half to get recovered".
Mathieu looks like he has really benefited from the match fitness he got at the exhibition event in Liverpool, after a convincing win over Gicquel and a hard-fought comeback against a disappointing and choke-filled Youzhny he battled past Thiemo de Bakker in a 4-setter that featured three breakers and some less-than-impressive thought processes and returning from the Dutchman.
The serve-dominated match featured just the single break of serve late in the fourth set the way of Paul-Henri, he seemed the more focused of the two and the one prepared to wait for his chances during the rally. de Bakker often erred with shot selection, misfired his execution and looked extremely sluggish with his footwork, movement and mental strength throughout the match.
After the match, the Frenchman explained; "I am playing well, everything is going right especially my serve and I feel good. It's easier to play when you are confident...I wanted to stay in my chair at the end of the match a little longer than usual. I haven't had many good wins this year. Touch wood this is the end of the barren spell"
Mathieu could definitely be the beneficiary of any Nadal physical issue, and it was clear enough in his last match to suggest that taking him at these short prices under his current circumstances is not worth the risk even if you can feel confident that he will never pull the pin unless he breaks a leg on the court (touch wood, of course).
Mathieu is 1-7 as a 7+ underdog beating Roddick in Montreal back in 2005, but has lost all five 4th round matches at Grand Slam level, has lost 21 of his last 23 against top 10 ranked guys and is just 4 wins from 11 matches against left-handers at all levels since 2009.
Nadal rarely loses these sort of matches and is a rock-solid sub 1.20 prospect especially at the majors, but caution must be treated with the state of his knees (and confidence/momentum/form). Mathieu is confident, in form and is a very good chance at the line and for the over games, providing he backs up physically which was a question mark from his last match.