A lob in tennis (also called Great Horse, in Italian Cavallone) is hitting the ball high and deep into the opponent's court. It can be used as an offensive or defensive weapon depending on the situation.
The lob was introduced by the second Wimbledon champion Frank Hadow in his defeat of Spencer Gore. For this reason Hadow was known as the "loftiest champion".
A lob is usually hit when an opponent is standing near the net, waiting to volley. The ball should sail over the top of the opponent and into the open court behind him or her. A good offensive lob cannot be reached by the opponent, yet it is low enough and has enough pace so that the opponent can not run back and chase it down. It can win the point outright, although with some risks involved. Topspin greatly enhances the effectiveness of offensive lob but also makes the stroke more difficult. When executing the lob, players usually hit the ball at an angle between 0 degrees (flat) and 45 degrees (diagonal). Some players, such as Andre Agassi, Michael Chang, and Lleyton Hewitt, have developed good offensive lobs.
A defensive lob, on the other hand, simply intends to push the opponent back to the baseline and prolong the point. When a player is pulled out of court, a defensive lob is also useful to buy time to run back and get into a better defensive position.
A lob that is not successful (can be reached by the opponent)(too shallow) is susceptible to being smashed.
In doubles, spin or slice is applied to the lob, so it will go over the head of a player at the net and bounce away from the baseline player.
Some players are able to manipulate a lob so that it appears the shot is overhit, but dips enough to fall within the baseline, often deceiving the opponent. This is created by generating a great amount of backspin, slicing or cutting the ball over the head of the other player. This shot, which can also be hit with tremendous topspin, is called a "moon volley or moon lob."