The prolific forward has recovered from ankle ligament damage and will join his club on Tuesday, but his Bundesliga comeback may have to wait until after Saturday's Rhine tieKoln are set to receive a boost in the coming days as star striker Lukas Podolski is poised for a return to training.
The 26-year-old has been missing since January due to an ankle injury, but is expected to resume exercises with the club on Tuesday.
However, coach Stale Solbakken fears that the player will not be fully fit to play this weekend, when Koln host Leverkusen in the Rhine derby.
"It is quite possible that we will have to play without [Podolski] on Saturday," the Norwegian trainer told Bild.
"We're creating no chances on goal and have problems in attack," he admitted.
Koln's 2-1 loss to Nurnberg on Saturday marked the Rhine side's fourth loss in five games since the winter break, leaving the club 14th in the Bundesliga. After the match, goalkeeper Michael Rensing admitted his side are in serious danger.
"We are now in the relegation battle," he said.
Podolski has scored 15 goals and given four assists in 18 Bundesliga games so far this season.