ALERTNESS IS everything. And never more important than on the big hands. Here is a case in point. It was seven-card stud high low, last hand of the night, so players were more than usually ready to gamble.

Stefan, who rather fancied himself as a smart player, raised on the opening round on !7, and then hit a !K. Next to him was a weak player showing a couple of middling cards, and, on the far side of the dealer, Doug, a solid enough player showing the potentially very good low hand 2-3.

On fifth street Doug caught a 10, which should have slowed him down. But instead he raised. Stefan who had hit a jack, hesitated and called. The third player, who did not have much money of front of him, came along. Sixth street Doug hit a deuce, to show a pair of deuces. As high hand he bet the pot, pounds 350. Again Stefan hesitated and called. The third man was all in for a mere pounds 50.

Doug: (x x) 22 #3 !10 42 (x); Stefan: (x x) !7 !K 4J 28 (x)

Here's the point of this story. Doug, in the last seat, behind the dealer, murmured: "I was bluffing." Stefan, on the other side, heard him say something but did not catch it. The dealer said: "There's more betting to come." Doug had been unable to see around the table that Stefan had more chips. "Oh!" he said, "I'll bet 100 all-in."

The dealer, an inexperienced young woman, should not have allowed this bet. After Doug's first remark he had to check, because under casino club rules talking is not permitted during the hand. But just as Doug had not seen Stefan had more chips, so Stefan had not heard Doug speak. Stefan folded. "I can't see you," he said. He had a four straight and four flush but no low .

Doug had only a pair of deuces for the high. He had hit a good low that vanquished the third player. Stefan - who should have been able to see the showdown for nothing, without any further betting - had hit a 7 last card to make a small pair on the end. If he had been fully alert, he would have taken half the pot.