The team was 13-2, ranked No. 8 in the nation and its No. 3 singles player had just contracted mononucleosis.

And someone had to take her place.

Freshman Ruth Barnes was that someone.

“I had mixed feelings about stepping into the lineup,” said Barnes, a native of England. “I wanted to have the chance to play and had been working all year, so I was at my absolute best in case anyone was injured. But I was upset for Shannon.”

Senior Shannon Duffy was diagnosed with mono March 16. The prognosis came just before the now-No. 12 Northwestern women’s tennis team’s toughest stretch of the season – a string of matches against No. 14 Fresno State, No. 11 California and No. 15 Baylor.

Thrust into the No. 6 singles spot, Barnes has performed admirably in two losing efforts, but the Wildcats (13-4) will need her point when Baylor visits Evanston Sunday.

NU freshman Stacy Kokx was sidelined with two torn ligaments in her hand, so Barnes was the only player who could fill Duffy’s spot.

“Even when (Barnes’) situation looked bleak in the middle of the year with everyone playing so well, Ruth stayed prepared and motivated,” coach Claire Pollard said.

“It wouldn’t have been so hard if we were not ranked as highly as we are. The expectations coming in are significant. We’d be lying to ourselves if we said it wasn’t difficult – it’s a team sport, but individuals really matter.”

Barnes lost in three sets in the matches against Fresno State and California.

Against California, Barnes took the first set before rain interrupted play.

“I felt like I had the match, then the other girl stepped up her play,” she said. “The break changed the match, but there was no specific mistake.”

Pollard said Barnes was not the reason the Cats lost the two matches.

“We win as team and lose as a team,” Pollard said. “Four people had to lose, not just one person. Ruth was right there with the opportunity to win. It was a huge positive knowing that she came so close against such a good opponent.”

Since joining NU in the fall, Barnes has had to adjust to the American style of play and cement courts rather than grass.

“The courts here are slower than in England,” Barnes said. “The ball bounces higher, and everyone I play has a lot of experience winning. Each player is more consistent.”

Barnes chose NU over Cambridge and Oxford Universities.

The reasoning behind her decision?

“There is nothing in England that is comparable in terms of tennis,” she said.

Barnes said she needs to put pressure on her opponent Sunday against Baylor.

“I need to make sure to use my weapon, which is my forehand,” Barnes said. “There is always an opportunity for your concentration to wander, but I need to focus and not give anything away.

“I need to fight as hard as I possibly can.”