Google, Inc. (NASDAQ: GOOG)is expected to post double-digit gains in profit and sales when it reports second-quarter results on Thursday as the company maintains a substantial lead in online search.

Analysts polled by Thomson Financial expect Mountain View, Calif.-based Google to post a 44 percent gain in earnings from the year ago period, reaching $3.59 a share, while revenue is expected to grow 60 percent to $2.68 billion.

During the quarter, the company has maintained its lead in online search, which drives its staple text-advertising product, Adsense.

Market researcher comScore Inc. said Google's sites captured 49.5 percent of June's U.S. search-engine market, with 4 billion search queries performed. The results were down from 50.7 percent in May, but still command a significant lead over the next 4 rivals combined.

Microsoft Corp. sites' share rose to 13.2 percent, or 1.1 billion searches, while IAC/InterActiveCorp's Ask Network's share was even at 5 percent, or 403 million searches.

Time Warner Inc.'s Time Warner Network, which includes AOL, had 341 million search queries, or 4.2 percent of market share.

Shares of Google fell 18 cents, or 0.03 percent to $552.81 in pre-market trading on Tuesday after rising 83 cents on Monday.