German defender Marcell Jansen put Hamburg in front less than three minutes after the start when he pounced on a rebound after Mladen Petric's initial drive.
But on the half hour, Köln skipper Youssef Mohammed rose to head home a Petit free kick, levelling the score at 1-1.
Petric, though, seized control of the match and restored Hamburg's lead five minutes later after a low cross from Jansen. He then added a second in the 50th minute from the penalty spot to make it 3-1.
Not to be denied, however, Köln set up a tense finish in the 75th minute when Milivoje Novakovic cut the lead to 3-2 on a sublime free kick that eluded goalkeeper Frank Rost.
Then, with just two minutes remaining, Köln secured an improbable point when Adli Chihi's deflected drive beat the outstretched Rost to complete the comeback.
BERLIN (AFP) - Hamburg's new star signing Ruud van Nistelrooy needs more time to get fit before making his Bundesliga debut, his coach Bruno Labbadia said on Wednesday.
Having spent most of the season on the bench at Real Madrid before signing for Hamburg 10 days ago, the 33-year-old Dutch hot-shot striker is only 60 percent fit, according to Labbadia.
And it looks as though the striker will sit out Hamburg's Bundesliga game at Cologne on Saturday and needs plenty of fitness work after knee surgery in November 2008 and having played just 127 minutes of football for Real this season.
"We would never put someone under a pressure of time to say when they will be fit," Labbadia told SID, a subsidiary of AFP, with his side fifth in the German league table.
"Ruud is still working his way back to fitness and it is only 60 percent.
"Whether or not he is in the squad, we will decide at the end of the week."
Labbadia says the Dutchman needs "a few more weeks" to return to top fitness.
"We don't want to rush him back too early and risk him getting injured," said Labbadia.
A calf injury meant van Nistelrooy only trained with the squad for the first time on Tuesday.
"He has not played for the best part of a year, it is a different story if a player has just been out for a few weeks."
Van Nistelrooy has signed a contract until June 2011 and Hamburg are reported to have spent four million euros on him.
He has already been crowned the best striker in Holland, having scored 62 goals for Eindhoven between 1998 and 2001, England, having scored 95 goals for Manchester United between 2001-06 and Spain, having netted 46 goals for Real between 2006 and 2010.
Having retired after Holland were knocked out of Euro 2008 by Russia in the quarter-finals, van Nistelrooy has said he would like to play for the Netherlands again at this summer's World Cup.