I don't think there is. One thing you could do, is drag the link to the current tab.

You can look at these prefs on the about:config page.

• http://kb.mozillazine.org/browser.link.open_newwindow (3)
• http://kb.mozillazine.org/browser.link.open_newwindow.restriction (0)

See http://kb.mozillazine.org/about%3Aconfig

Some extensions that you can look at:

• Tab Utilities Lite: https://addons.mozilla.org/firefox/addon/62581
• Tabberwocky: https://addons.mozilla.org/firefox/addon/14439
• Tab Mix Plus: https://addons.mozilla.org/firefox/addon/1122

Maybe it's not your matter, but after install some Add-ons, they modify the behavior to always open links in new tabs.

A example of that is when you install Tab Utilities, you need to go to its configuration, and in Links field, deselect "Force all links to open in New Tab".