 Federer struggled with back injuries sustained in March and again in July and saw his ranking drop from No. 2 to No. 6 . The 2013 season was the first since 1999 in which Federer failed to reach a final in the first four months of the year . 
 Federer struggled with back injuries sustained in March and again in July and saw his ranking drop from No. 2 to No. 6 . The 2013 season was the first since 1999 in which Federer failed to reach a final in the first four months of the year . 
Federer struggled w bk injuries sustained in March and again in July and saw his ranking drop from No. 2 to No. 6 . da 2013 season was tdafirst since 1999 in which Federer failed to reach a final in the first 4 months of the year .