Katoto, who is PSG's all-time top scorer at the age of just 23, netted a 20th-minute opener and then headed home in the 71st minute for the French champions at the Allianz Arena.
However, German international Klara Buehl smashed in a late free-kick to keep Bayern's hopes alive going into the return.

PSG's women are hoping to go all the way in Europe after ending Lyon's run of 14 consecutive French titles last season.

The two-time runners-up went in front when Kadidiatou Diani turned a Sara Daebritz corner against the bar and, in the ensuing scramble, Katoto fired in from the edge of the six-yard area.

PSG -- whose only defeat so far this season was a 6-1 reverse in Lyon in November -- then suffered a blow as former Bayern player Daebritz was forced off injured before the interval.

They had goalkeeper Barbora Votikova to thank for getting down low to keep out a Buehl shot midway through the second half, and soon after that the away side doubled their lead.

Sandy Baltimore swung in a corner from the right and Katoto headed in with goalkeeper Janina Leitzig having committed herself.

Votikova then tipped a Sydney Lohmann header onto the post but Bayern reduced the deficit with seven minutes remaining as Buehl's free-kick from 20 metres out proved too powerful for the Czech goalkeeper.

That goal means Bayern will head to Paris for the return leg next Wednesday with some optimism, while PSG could be on a collision course with Lyon in the semi-finals.

The French rivals will meet in the last four if they both advance, with Lyon facing Juventus in Italy in the first leg of their quarter-final on Wednesday.

Lyon have won the Champions League a record seven times, including a run of five in a row that was broken by Barcelona last season.

Barca are heavy favourites to beat Real, having beaten them 5-0 earlier this month to wrap up the Spanish title.

They have won all 24 games so far in their domestic league this season and won all six Champions League group games, while Real are fifth in the Spanish league.

The winner of that tie will go through to a semi-final against English Women's Super League leaders Arsenal or Wolfsburg, who qualified for the last eight at Chelsea's expense.

They meet in their quarter-final first leg on Wednesday.