What is invisible is what's called a Crane - with a ladder.
Soccer legend Diego Maradona of Argentina hugs tennis player, Juan Martin Del Potro, also from Argentina, after an exhibition tennis match, during the Dubai Duty Free Tennis Championships, in Dubai, United Arab Emirates Wednesday, Feb. 27, 2013. (AP Photo/Regi Varghese)
Spain?s Rafael Nadal celebrates after defeating Argentina?s Diego Scwartzman during the Mexican Open Tennis in the Pacific resort in Acapulco, Tuesday, Feb. 26, 2013. Nadal won 6-2, 6-2.(AP Photo/Christian Palma)
Spanish?s David Ferrer returns the balll to Croatia's Antonio Veic during the Acapulco Tennis Open in the Pacific resort in Acapulco, Tuesday, Feb. 26, 2013. (AP Photo/Christian Palma)
Federal police officers patrol before the start of the Mexican Open tennis tournament outside the Mextenis stadium in the Pacific resort city of Acapulco, Monday, Feb. 25, 2013. Acapulco has been hit by violence as drug gangs continue to battle for control of the region. (AP Photo/Christian Palma)