AT&T’s 5,000-strong sales force will begin to sell Yahoo’s display inventory in local ad markets starting later this summer, under a new partnership the two companies announced Tuesday. During Yahoo’s earnings call, CEO Carol Bartz boasted that the relationship means that Yahoo (NSDQ: YHOO) will now have 13,000 local ad sales reps located across the United States. But the partnership could create new competition for many of Yahoo’s existing reps who work for members of the Yahoo Newspaper Consortium, since there is likely to be overlap between the local businesses the two groups will sell to. In an interview with ClickZ, Yahoo SVP Jim Schinella dismisses those concerns saying that newspaper and directory companies have long competed in the same markets and they “naturally gravitate toward different business partners.”