The top-selling sketch, Bajar rinendo, sold for twice its estimated price
Three drawings by Spain's Francisco de Goya, presumed lost for 130 years, have fetched more than £4m at auction.
The three sketches, drawn between 1812 and 1829, had not been seen since 1877.
The top lot, Bajar rinendo (Down they come), shows four women fighting. It sold for £2,2m, a world record auction price for a Goya work on paper.
The auction, at Christie's in London, also saw La Surprise, by French artist Jean-Antoine Watteau, sell for £12.3m - another world record.
The painting, an 18th Century masterpiece, was discovered hanging on the wall of an English country home last year.
The other two Goya sketches depict a constable stitched inside a dead horse and a wide-eyed man praying in front of a cross.
The pieces, all from the artist's celebrated notebooks, were discovered in a private Swiss collection.
Watteau's La Surprise had been missing for almost 200 years
Watteau's La Surprise, which shows a musician tuning his guitar as he sits next to an amorous couple, had been expected to fetch £5 million.
Christie's said it was "thrilled" to see the painting fetch more than £12 million, the highest price paid for any French old master painting sold at auction.
Tuesday's event will be followed on Wednesday by another old masters sale at rival auction house Sotheby's.
Highlights include an oil painting portrait by Dutch artist Frans Hals and a painting by JMW Turner that has not appeared on the open market since 1827.
The artwork, entitled Pope's Villa At Twickenham, has a pre-sale estimate of up to £7 million.