Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Date | Championship | Surface | Opponent | Score |
| --- | --- | --- | --- | --- | --- |
| Runner-up | 1971.0 | Merion , U.S. | Hard | Clark Graebner | 2–6, 4–6, 7–6, 5–7 |
| Runner-up | 1973.0 | Miami WCT , U.S. | Hard | Rod Laver | 6–7, 3–6, 5–7 |
| Winner | 1974.0 | Atlanta WCT , U.S. | Clay | Jiří Hřebec | 6–2, 6–1 |
| Runner-up | 1974.0 | Charlotte , U.S. | Clay | Jeff Borowiak | 4–6, 7–5, 6–7 |
| Winner | 1974.0 | Adelaide , Australia | Grass | Geoff Masters | 6–2, 6–3, 6–2 |
| Runner-up | 1975.0 | Fort Worth WCT , U.S. | Hard | John Alexander | 6–7, 6–4, 3–6 |
| Winner | 1975.0 | San Antonio WCT , U.S. | Hard | Stan Smith | 7–5, 2–6, 7–6 |
| Runner-up | 1975.0 | Washington Indoor WCT , U.S. | Carpet | Mark Cox | 2–6, 6–7 |
| Winner | 1976.0 | Lagos WCT , Nigeria | Clay | Arthur Ashe | 6–3, 6–2 |
| Runner-up | 1976.0 | Sydney Outdoor , Australia | Grass | Tony Roche | 3–6, 6–3, 3–6, 4–6 |
| Winner | 1977.0 | Philadelphia WCT , U.S. | Carpet | Jimmy Connors | 3–6, 6–4, 3–6, 6–1, 6–2 |
| Winner | 1977.0 | Toronto Indoor WCT , Canada | Carpet | Jimmy Connors | 5–6, RET. |
| Winner | 1977.0 | Rotterdam , Netherlands | Carpet | Ilie Năstase | 2–6, 6–3, 6–3 |
| Runner-up | 1977.0 | Dallas WCT , U.S. – WCT Finals | Carpet | Jimmy Connors | 7–6, 1–6, 4–6, 3–6 |
| Runner-up | 1978.0 | Birmingham WCT , U.S. | Carpet | Björn Borg | 6–7, 5–7 |
| Winner | 1978.0 | Little Rock , U.S. | Carpet | Hank Pfister | 6–4, 3–5, RET. |
| Runner-up | 1978.0 | San Francisco , U.S. | Carpet | John McEnroe | 6–2, 6–7, 2–6 |
| Runner-up | 1981.0 | South Orange , U.S. | Clay | Shlomo Glickstein | 3–6, 7–5, 4–6 |
Question:
During what Championship was the Opponent Jeff Borowiak?
Answer:
Charlotte , U.S.