With regards to Tipsarevic, he had the benefit of being a top eight seed this year at the US Open, and Ferrer was his opponent in the quarter-finals. A golden opportunity, indeed.
With Nadal coming back, that pushes Janko out if the top eight, and also means he'll more than likely have to beat a top four member to reach the semi-finals. Something I don't think he's capable of in a grand slam.
Not unless he drops out of the top 12. Matches according to seeding:
R16: 5-8 play 9-12 and 1-4 play 13-16
QF: Winners of 5-8,9-12 play winners of 1-4,13-16.
Almagro has a better chance in my opinion, he's younger and has much more of a specialist Slam (needed for a big run). Almagro has beaten Murray at Roland Garros before (in 2008) and has been unlucky to draw Nadal in each of his best Roland Garros runs.