Ninth-placed Central Coast Mariners held Sydney FC to a 1-1 draw two months after upsetting the defending A-League champions 2-0 in Gosford.
Back in their home fortress of Allianz Stadium, Saturday night was supposed to be about revenge.
It amounted to another example of the Sky Blues on an off night against a Mariners side willing to put men behind the ball and restrict their forward movement.
Fortunately for Graham Arnold on his 200th coaching appearance, Bobo's second-half header saved the day - and Sydney's now 25-match undefeated streak at Allianz Stadium.
However, it means the league leaders only go seven points clear of Newcastle instead of the nine on offer.
A calamitous Sydney error gifted the visitors a penalty goal in the seventh minute.
Josh Brillante sold Andrew Redmayne short with a backpass and the goalkeeper fouled the onrushing Kwabena Appiah on his way out to collect, leaving Blake Powell to slot home from the spot.
Sydney were guilty of playing tentatively despite being put under little pressure.
There were chances; Milos Ninkovic skewed a shot high, Alex Brosque was denied by Ben Kennedy and Bobo scored a would-be equaliser from an offside position.
It was a far sight from their usual fearless attacking play.
The Mariners would have doubled their lead and won had Lachy Wales not executed the miss of the season from Sydney's goalmouth in the final kick of the first half.
It was just as well for Sydney, who could thank one outstanding passage of play for the result.
Adrian Mierzejewski's ball landed flush on Bobo's head and he directed it over Kennedy's head to leave the bewildered gloveman on the ground.
In an occasion to savour for the Brazilian striker, his 16th goal of the season brings him equal with Marc Janko's club record for most goals in a single campaign.