[pic:CBS SPORTS]

World Boxing Organization welterweight champion Terence Crawford is again calling out IBF and WBC champ Errol Spence Jr.

This is after Crawford beat Shawn Porter by 10th-round TKO yesterday.

Porter has since confirmed his retirement, Crawford has proven himself against elite competition and yet one question still remains.

Crawford, who was on the final fight of his deal with Top Rank, confirmed post-fight that his he would not be renewing his contract.

PBC, who Spence and fellow champion Yordenis Ugas fight under, is the likeliest option to secure the Spence fight.

Crawford was surprised when informed that Spence was in attendance in yesterday’s fight.

The 34-year-old American says he’s been calling Spence out all day.

There have been roadblocks along the way to any potential fight, with Spence involved in a serious car crash and also recently pulling out of a bout with Manny Pacquiao due to a retina problem.