Tennis cards, like baseball cards? Yes and no.
These are called cigarette cards. Not much bigger than a modern business card, these trade cards were a bonus in a pack of cigarettes. They came in a series, usually twenty-five or fifty, with a similar theme.

Many were aimed at male smokers: airplanes, sports and cars. These cars were modern at the time.
Cigarette companies wanted brand loyalty from consumers, so they gave them tiny works of art.

Another good way to get customers to keep buying from their company, and not from a competitor, was to display numbers on the cards.
Or even letters of the alphabet.

The cards above and below are part of a 1910 series, Boy Scouts and Girl Guides.
Some were embroidered silk. Recently, a quilt made of many of these was on display at the Pasadena Museum of History.
I came across all of these, and many more, by accident, at a hotel near Yosemite, the Yosemite View Lodge in El Portal. All of the ones there were from Great Britain, from 1890 to 1939. The cigarette cards below of British military uniforms were issued in 1939, when the country was fighting for its survival in World War II. I like to imagine people in a bleak time appreciating the small, patriotic works of art.