Safin is currently ranked 151 in doubles [he peaked at 71 in 2002]. However, the reason why his ranking is so low is because he plays doubles so infrequently. If he played on a regular basis I'm sure he'd be in the top 50. This year, his ATP doubles highlights are making the semis of Estoril and Halle and the quarters of Cincinatti. He's never played before with Lopez prior to this tournament.
Lopez plays doubles a lot more regularly, quite a few times with Nadal. He's not played so much this year as his ranking has dropped to 119. His highest was 37 in 2004. His best result this year has been reaching the Estoril semis with Verdasco. He and Verdasco also won a match in the Aussie Open. He and Nadal lost in rd1 of Queens to Auckland and Delgado. He's struggling form-wise at the moment, he got thrashed in rd1 by Srichaphan.
The match is 5th on court 1 at approximately midday.