Sport is a mental and physical challenge. And here with these Spot the Difference puzzles, we have a fun challenge for you.

In each of these vintage sports photographs, you'll find six changes that we have made. Some may be small and subtle, so look closely.

We suggest right-clicking to see the image larger in another tab and, if you need some help, at the end of the blog, you'll find a link which reveals the results.

Bulgaria

This crowded photograph shows athletes and members of Sporting Club Vladislav in Varna, Bulgaria. The photograph was taken in the 1920s.

The original is the first below - can you spot the 6 changes in the second image?

The Netherlands

This photograph is from 1992 - a rugby match in s'Hertogenbosch, The Netherlands between two clubs: The Dukes and the Utrecht Student Rugby Society.

Finland

The people in this photograph are members of the Kristinestad Sports Association. Kristinestad is a city in western Finland, and the photograph was taken in the 1920s.

Czechoslovakia

These are the female members of the Czechoslovak Olympic team for the 1936 Olympic Games. They are wearing clothing from a company called Rolný. (Incidentally, you can also see the male team members in a similar photoshoot.)

Cyprus

Athletes representing Cyprus took part in the Olympics for the first time in the 1980 Games in Moscow, parading in the opening ceremony on 19 July 1980.

Estonia

On your marks, get set, go... a steward checks the starting line at the beginning of the Tallinn Olympic Race in Estonia in 1993.