This Cubs season is beginning to have the look of a 20-car pileup on the expressway.

You can see a collision coming in the rear-view mirror, but there's nothing you can do to prevent it.

And so it went again on a humid Friday night at RFK Stadium when Mark Prior stumbled in his first start off the disabled list and Bob Howry blew a two-run lead in the eighth inning as the Cubs helplessly watched Washington bounce off the mat for a 7-6 victory before a crowd of 35,442.

"Boy, that was a tough one," Cubs manager Dusty Baker said.

The Cubs also wasted a two-homer night by Aramis Ramirez, while Prior's return ended in disaster.

In his first start since suffering a left oblique strain July 8 in Milwaukee, Prior failed to get out of the fourth inning. Now winless in his last eight starts dating back to 2005, Prior allowed four runs on four hits in 31/3 innings, issuing three walks, throwing two wild pitches and hitting a couple of batters.

Prior blamed it on a lack of pitching.

"The best way I can describe it is like playing golf," Prior said. "You can go out and play, but your short game is not going to be there. There would be situations where I get ahead 0-2, or 1-2, but I don't have that touch, basically, to put guys away."

After the Cubs had scrambled back to take a 6-4 lead, Howry replaced Scott Eyre in the eighth—after Eyre faced one batter and left because of a tight right hamstring—and was victimized by a rally that could have been drawn up in crayon: a broken-bat hit, a single up the middle, a foul-ball sacrifice fly to the second baseman, a blooper to center and a two-run single to left that allowed slow-footed Nick Johnson to score from first base.

"Howry has been great all year," Baker said. "He was the right man in the right spot. You just can't control cheap hits."

After the Nationals whittled the deficit to one in the eighth on Ryan Zimmerman's pop foul sacrifice fly to Todd Walker, Johnson followed with a blooper to center and Alex Escobar drilled a single down the left-field line.

As Marlon Anderson scored the tying run from second, Johnson stumbled around third base while being waved home when Matt Murton bobbled the ball in left.

"They were going to send him anyway," Baker said. "Johnson stumbled halfway. If [shortstop Ronny Cedeno's] throw was on, he would have been out. But the relay throw was off. I thought we had a heck of a chance."

Prior hit Alfonso Soriano in the left shoulder leading off, watched him steal second on the next pitch, walked the next batter and threw a one-out wild pitch that advanced both runners. After Johnson struck out on a high fastball, Prior uncorked another wild pitch, allowing Soriano to score.

Anderson's two-out, bases loaded double over Murton's head on a 1-2 pitch in the second cleared the bases, giving the Nationals a 4-1 lead.

After the Cubs cut the deficit to one, Walker's RBI groundout and Ramirez's two-run shot off Kevin Gryboski put the Cubs ahead 6-4 in the seventh before the Nationals stormed back.

psullivan@tribune.com