* Former winners Lithuania sink Italy
* Croatia prove too strong for Ukraine (Updates after Lithuania win)
LJUBLJANA, Sept 19 (Reuters) - Former winners Lithuania and perennial underachievers Croatia overpowered their opponents on Thursday to march into the semi-finals of the European Championship.
Lithuania, champions in 1937, 1939 and 2003, produced a strong final quarter to outmuscle Italy 81-77 in the Stozice Arena to set up an intriguing clash with Croatia on Friday.
Earlier, Croatia ended an 18-year wait to reach the last four with a comfortable 84-72 defeat of underdogs Ukraine.
"We bounced back into the top echelons of European basketball in grand style and we don't want to stop here," Croatia coach Jasmin Repesa told state television HRT.
"The semi-final is an opportunity to get the just rewards for our hard work."
Holders Spain, aiming for a third successive title, and 2011 runners-up France will meet in the other semi on Friday.
An Italian team lacking the muscle of their NBA centre Andrea Bargnani, who joined the New York Knicks from the Toronto Raptors in July, held their own for three quarters against their physically superior rivals before succumbing early in the final period.
Lithuania's resolute defence kept their opponents scoreless for six minutes in the fourth quarter, conjuring a 15-0 run to take an unassailable 72-58 lead on the back of 17 points apiece from guard Mantas Kalnietis and forward Renaldas Seibutis.
San Antonio Spurs acquisition Marco Belinelli topped the scoring with 22 points and his Italy team launched a final push in the closing stages but a lack of size under the boards cost them dear as Lithuania ended up with 13 rebounds more than their rivals.
Croatia celebrated an eighth straight win earlier, following a crushing 68-40 opening group stage defeat by Spain, to set up a repeat of the 1995 semi-final against Lithuania.
The Croatians, who finished third in that tournament to win their only medal as an independent nation, dominated the Ukrainians after overturning a 12-5 deficit thanks to a superb individual performance by Krunoslav Simon, the game's top scorer with 23 points.
Trailing by three points midway through the second quarter, Croatia produced a 19-1 surge and although the Ukrainians fought hard to stay in touch they had no answer to the versatile Simon.
"We were the better team and turned the match our way before halftime which should mean we have plenty left in the tank for the semi-finals," said captain Roko Leni Ukic. (Writing by Zoran Milosavljevic in Belgrade; editing by Tony Jimenez)