The blue-chip FTSE 100 index, which rose 0.7 percent on Wednesday, slipped 0.05 percent, or 3.37 points, to 6,568.87 points by 0748 GMT.
A 4.5 percent fall for Diageo, after weakness in its Chinese market led to lower third quarter sales, took the most points off the index.
"The slowdown in Asia and China is hurting a lot of these big companies, such as Diageo, which have based a lot of their future growth on these markets," Brown Shipley fund manager John Smith said.
"We're comfortable with holding Diageo for the long-term, as it has good brands, but for the short-term, it's clearly suffering," he said.
The FTSE 100, which rose 14.4 percent last year, is down by about 3 percent since the start of 2014.
The index reached a peak of 6,867 points in January this year, its highest since early 2000, but it has since dropped on concerns over a slump in emerging markets and fears over fallout from tensions between Russia and Western powers over Ukraine.
Strand Capital managing director Kyri Kangellaris saw the FTSE stuck in a range of 6,500-6,850 points, as long as it failed to break above its January high of 6,867 points and last year's peak of about 6,876 points.
"We're looking rangebound for the near term," he said.