Karlovic and Cilic give Croatia 2-0 lead over U.S

POREC, Croatia (Reuters) - Croatia took a commanding 2-0 lead in their Davis Cup quarter-final by winning two five-set marathons on Friday.

Ivo Karlovic put Croatia one up after coming back from two sets down to beat James Blake 6-7 4-6 6-3 7-6 7-5 after three hours and 38 minutes.

Croatia's number one Marin Cilic then prevailed 4-6 6-3 6-7(3) (6-1) 8-6 over a gallant Mardy Fish, who was brought into the U.S. team to cover injured Wimbledon finalist Andy Roddick.

After narrowly winning the first set, 17th-ranked Blake broke Karlovic early in the second to rush to a two-set lead.

But the towering Croat clubbed three winners to break Blake in the second game of the third set, and closed it out as his serve and volleying came to the fore.

Karlovic took the fourth in a tie-break, then broke his opponent in the 12th game of the final set to make sure of the result.

"I was a bit nervous at the start, playing before the home crowd, but I became more relaxed as the match went on, and I managed to turn it around. This is surely one of the biggest matches in my career," Karlovic said after the match.

After losing the first set in a hail of unforced errors and poor serving, world number 15 Cilic broke Fish twice in the second to square the ledger.

After losing the third in a tie-break, Cilic appeared to have all the momentum going into the decider, steam-rolling Fish 6-1 in the fourth, but the American dug deep, breaking back after surrendering his serve at 4-3 in the fifth.

Fish eventually capitulated in the 14th game, however, to put the hosts in the box seat ahead of the doubles on Saturday.

Croatia's Ivo Karlovic and Lovro Zovko are set to take on the world's number two pair Mike and Bob Bryan.

The United States, 32-time Davis Cup winners, have lost both of their previous encounters with Croatia.

"It's been two great matches, and two tough losses. Both Croatian guys played great and managed to come back, but hopefully we'll get the doubles tomorrow," U.S. team captain Patrick McEnroe said.

(Reporting by Zlata Zsolnay; Editing by Ian Ransom)