If being No. 2 still means you try harder, then Hong Kong has a big job on the waterfront.

In the first quarter of this year, Hong Kong was knocked off its perch of three years as the world's busiest containerport by Singapore, according to figures obtained Tuesday by The Journal of Commerce from the Port of Singapore Authority.While three-month figures aren't necessarily a harbinger of the year, comparative growth rates clearly indicate Hong Kong is losing ground.

Steamship lines that call at Hong Kong are afraid the shift could prompt officials to delay building new box terminals there.

"If we aren't No. 1, there may be less government concentration on the need for expansion," explained Brian Conrad, secretary of the Hong Kong Liner Shipping Association, which represents port users. "Officials may think it isn't necessary. That's short-sighted," he told The Journal of Commerce.

"Even if growth is slower, it is there, and we need to be the best if not the busiest," he said Tuesday.

Hong Kong's acting marine director, Alan Pyrke, wasn't available for comment, but his public relations aide pointed out that port development is incremental.

"It's not like the (new) airport, where everything must be ready at once," said Chris Yip. "We can add port facilities as and when the demand warrants, accelerating or decelerating in line with conditions."

Port officials in Singapore make a point of not trumpeting their volume statistics. The port doesn't even formally announce its box volumes but releases the figures only to specific parties who ask for them.

The Singapore port said it processed the equivalent of 1.21 million 20-foot boxes, known as TEUs, in the first three months of 1990. Throughput in Hong Kong for the first three months was 1.06 million TEUs, according to figures released earlier this month by the colony's Marine Department.

Hong Kong's growth was 10 percent over the corresponding period of 1989, the Marine Department said; Singapore's about 20 percent, according to the Port of Singapore Authority.

For all of last year, Hong Kong barely clung to its top-rated position with throughput of 4.46 million TEUs, an increase of 10.6 percent on the 4 million TEUs of 1988. Singapore handled 4.36 million TEUs, up 30 percent.

Singapore cargo growth rate has outstripped Hong Kong's for many months. It is benefiting from the booming economies of its neighbors whose port facilities aren't as good, notably Thailand and Malaysia, and from lower rates charged by the state-run port body.

Hong Kong, whose container facilities are privately run, is a comparatively expensive place to load and unload. Singapore charges 60 percent of Hong Kong's fees for handling a box. The Port of Kaohsiung in Taiwan charges between 50 percent and 60 percent of Hong Kong's rates.

In addition, Hong Kong's trade is slowing, particularly exports, a trend expected to continue through this year.

China business, which accounts for perhaps 40 percent of Hong Kong's port activity, also shows signs of slowing. In the first quarter, exports to China were up just 1 percent over last year and re-exports down 11 percent. Imports grew 13 percent, but much of that cargo comes down by road or rail.

Hong Kong could end the year with throughput of 4.9 million TEUs, based on anticipated 10 percent growth, against Singapore's 5.2 million TEUs on growth of 15 percent, which is probably conservative.

Both ports are expanding facilities, though in Hong Kong's case there is some disquiet about the scale because of reduced growth.

Singapore is spending S$1 billion (US$500 million) on a new container terminal with feeder berths and other backup facilities to be ready in 1996. It will offer 4 million TEUs' capacity, adding to the 6 million available at Tanjong Pagar, the current main box terminal.

Hong Kong has announced plans for two new container terminals by 1995 at a cost of HK$50 billion (US$6.4 billion). They will have six berths, adding 2.4 million TEUs of capacity to the roughly 5 million now available.

There is some feeling that being No. 1 has a nice ring to it but isn't all that important in itself. The Hong Kong Liner Shipping Association doesn't share that blase view.

"Terminals 8 and 9 and even 10 are still definitely needed despite the slower growth," said Mr. Conrad.