Germany and Belarus claimed two gold canoeing medals apiece on Friday at Beijing's Shunyi Olympic Park.
Germany won the women's K4 500m to remain undefeated in that event since 1992 and took another gold in a close-run men's K2 1000m.
Belarusian crews in the men's C2 1000m and men's K4 1000m also fought hard to claim gold in both events.
Hungary's Attila Sandor Vajda won the men's C1 1000m as Britain's Tim Brabants took the men's K1 1000m.
Vajda, 25, took the lead at the 750m mark and injected a late surge of pace to cross the line in three minutes 50.467 seconds.
Spain's defending champion David Cal paid the price for a poor start and could not reel in Vajda, settling for silver in 3:52.751.
Canada's Thomas Hall collected bronze just edging out early pacesetter Vadim Vadim Menkov of Uzbekistan.
Fanny Fischer, Nicole Reinhardt, Katrin Wagner-Augustin and Conny Wassmuth successfully defended Germany's women's K4 500m crown with a dominant display.
The quartet charged out of the starting blocks and went unchallenged as they won in 1:32.21.
Hungary collected silver as Australia edged out a fast-finishing Poland quartet for bronze.
Fischer and Reinhardt will go for double gold in the women's 500m kayak double final on Saturday.
Martin Hollstein and Andreas Ihle kept up the gold medal rush for Germany as they won the K2 1000m crown.
Hungarian favourites Zoltan Kammerer and Gabor Kucsera flew through the first 500m but were overhauled by the German pair in the final 200m.
Denmark came through for silver thanks to Kim Wraae Knudsen and Rene Holten Poulsen as Italian duo Andrea Facchin and Antonio Massimiliano Scaduto claimed bronze with Hungary fifth.
Belarus began a gold rush of their own when brothers Andrei and Aliaksandr Bahdanovich pushed all the way to the line to grab gold from Germany in the men's C2 1000m.
German duo Christian Gille and Thomasz Wylenzek held on for silver as Hungary's Gyorgy Kozmann and Tamas Kiss took bronze.
Kozmann and Kiss wore black armbands as a mark of respect for double canoeing Olympic gold medallist Gyorgy Kolonics, who died last month after collapsing in his canoe while training for the Games.
The Belarusian quartet of Raman Piatrushenka, Aliaksei Abalmasau, Artur Litvinchuk and Vadzim Makhneu added a second gold in the men's K4 1000m race that went right down to the wire.
With Slovakia, Belarus and Germany all still in contention in the dying stages, Slovakia edged ahead of Belarus only for the Belarusian kayak to come back again.
Slovakia took silver with Germany's Lutz Altepost, Norman Brockl, Torsten Eckbrett and Bjorn Goldschmidt claiming bronze.
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