The Australian told BBC Sport: "We are pleasantly surprised with the result and how close it was. [Mercedes] were a fair way in front yesterday but today it was only two tenths. We thought Mercedes had more in the bag so that's going to be interesting.
"It's tricky to overtake here but we have got a chance to race them tomorrow. It could be on! It's nice there are more teams closer to pole this weekend so it will make the race more exciting."
Ricciardo has won three races so far this season, and sits third in the drivers' standings.