* Belavia is ninth new client in region, sixth since 2010
* Executive sees more growth on the turf of Russian rival Sukhoi
* Embraer looks to U.S. carrier negotiations for big order
SAO PAULO, Sept 13 (Reuters) - Brazil's Embraer, the world's largest maker of regional jets, is set to deliver its first plane to Belarusian carrier Belavia on Thursday as part of a recent push into the backyard of an upstart Russian rival.
Belavia is the ninth airline to fly Embraer's regional E-Jets in Eastern Europe and Central Asia and the region's sixth new client since 2010 -- a pace of growth likely to continue in coming years, according to a senior Embraer executive.
"There is no doubt we have space to add new clients in Eastern Europe, Central Asia and even Russia itself. Why not?" said Paulo Cesar de Souza e Silva, the head of Embraer's commercial aviation unit, in a phone interview.
That drive puts Embraer in the backyard of Russian plane maker Sukhoi. That company's new regional Superjet has more than 200 firm orders but faces challenges as authorities investigate a May crash that killed 45 in Indonesia.
New frontiers are increasingly important for Embraer as demand dries up in Western Europe, where it has sold hundreds of E-Jets in the family's decade of service.
The plane maker booked about one new regional jet order for every three it delivered in the first half of this year, draining its pipeline of future revenue to the lowest level since 2006.
Analysts have warned that without a major new E-Jet order the company may have to scale back production next year, hurting revenue. But Chief Executive Frederico Curado said in July the company still has no plans to cut regional jet output.
Silva said the best prospect for a big new order is in the United States, where Delta Air Lines, United Continental and American Airlines have been negotiating with unions to allow for larger regional jets.
"To keep up the pace, obviously that depends on new orders and also when those deliveries would happen," he said.