The 31-year-old Georgian, who scored the second goal, said: "The result in Sofia and the way we played has given us much more confidence to play well in the Premiership."
Ketsbaia, who had been out of action with a back injury, came off the bench to replace Duncan Ferguson with just 18 minutes played in Sofia, and he slid home the second goal with 13 minutes left after the Peruvian Nolberto Solano had put the visitors in front with a perfect free-kick.
The Georgian admitted the win had come as a huge relief. "It was very good," he said. "It was our first win for a very long time. We played very well in the second half and we deserved to win. It was difficult for me because I have not played for three weeks, so it was great to come back and score a goal.
"But what is more important is that we won the game. It was important for us to get a result to get us away from this situation we are in, but we're also looking to play good football."
Oyvind Leonhardsen has, he believes, rescued his career by moving to Tottenham. The Norwegian midfielder was struggling at Liverpool before his pounds 3.5m summer move to White Hart Lane, where he has found his best form.
Thursday's goal against Zimbru Chisianu in the Uefa Cup took his tally to three goals in six starts for his new club. "I am very pleased that I have had a good start here and I am really enjoying myself," Leonhardsen said. "I have also scored two goals in as many games for Norway. I have a good record in the national side and it is going well for me this season.
"Things seem to have worked out well. I feel I have settled in quite quickly. George Graham is a great manager and his style of play suits me. The fans have been fantastic and that has given me confidence. We are a strong team and can beat anyone on our day so we want to go as far as we can - a three-goal cushion should be enough to see us through the second leg in a fortnight."
Graham had asked Tottenham fans to be patient in case an early goal against the Moldovan part-timers failed to arrive, but Leonhardsen produced a stunning finish after just three minutes to set Spurs on their way to a comfortable 3-0 first-leg victory.
West Ham overturned the Croatians of Osijek by the same margin at Upton Park, and their Croatia defender, Igor Stimac, is looking forward to the return leg with confidence.
Stimac said: "We played brilliantly and scored three great goals. We can take it easy now. It will be easier to play over there because they are better at defending than attacking."
Stimac, who has played 40 times for Croatia, said the city of Osijek had been badly damaged by fighting during the Balkan wars, but he insisted West Ham would receive a warm welcome. "There will be a nice ground and a good pitch," he said, "but we will see this city has been affected very much by the war because it is near the border with Serbia."